Non-aqueous liquid electrolyte and non-aqueous liquid electrolyte secondary battery using the same

ABSTRACT

A non-aqueous liquid electrolyte to be used for a non-aqueous liquid electrolyte secondary battery containing a anode electrode and a cathode electrode, capable of intercalating and deintercalating lithium ions, and the non-aqueous liquid electrolyte. In the non-aqueous liquid electrode, the anode electrode contains an anode electrode active material having at least one kind of atom selected from the group consisting of Si atom, Sn atom and Pb atom. The non-aqueous liquid electrolyte also contains a carbonate having at least either an unsaturated bond or a halogen atom, and also contains a compound represented by formula (III-1) as defined herein.

TECHNICAL FIELD

The present invention relates to a non-aqueous liquid electrolyte andnon-aqueous liquid electrolyte secondary battery using the same.

BACKGROUND ART

Recently, with the reduction in weight and size of electricalappliances, development of a non-aqueous liquid electrolyte secondarybattery having high energy density, for example lithium secondarybattery, has been advanced. Also, as application field of lithiumsecondary battery is expanded, further improvement in its batterycharacteristics has been desired.

In this situation, a secondary battery based on metal lithium as anodeelectrode has been studied as a battery capable of achieving highercapacity. However, there is a problem that metal lithium grows asdendrite on repeated charges and discharges, and when this reaches thecathode electrode, shortings in the battery occurs. This has been thegreatest obstacle in realizing a lithium secondary battery based onmetal lithium as anode electrode.

On the other hand, a non-aqueous liquid electrolyte secondary batteryhas been proposed, in which carbonaceous material capable ofintercalating and deintercalating lithium, such as coke, artificialgraphite or natural graphite, are used for the anode electrode in placeof metal lithium. In such a non-aqueous liquid electrolyte secondarybattery, growth of metal lithium as dendrite can be avoided and batterylife and safety can be improved. When graphite of these kinds are usedas anode electrode, capacity is known to be usually of the order of 300mAh·g⁻¹, 500 mAh·cm⁻³.

Recently, proposals have been made for the anode electrode activematerial based on simple metal element capable of forming an alloy withlithium such as Si, Sn and Pb, an alloy containing at least one of thesemetal elements, or metal compound containing these metal elements(hereafter referred to as “anode electrode active material containingSi, Sn, Pb and the like”, as appropriate). The capacity of thesematerials per unit volume is of the order of 2000 mAh·cm⁻³ or larger,which is about 4 times or even larger than that of graphite. Therefore,higher capacity is obtained by using these materials.

Although a secondary battery using anode electrode active materialcontaining Si, Sn, Pb and the like is suitable for realizing highercapacity, there is a decrease in safety, and anode electrode activematerial deteriorates on repeated charges and discharges, leading toreduced charge-discharge efficiency and deterioration of cyclecharacteristics.

Therefore, in order to secure safety and prevent a decrease in dischargecapacity, a proposal has been made to include cyclic carbonate ester ora polymer of carbonate ester and phosphoric acid triester in thenon-aqueous liquid electrolyte used for a secondary battery (PatentDocument 1). Furthermore, a proposal has been made to add, in thenon-aqueous liquid electrolyte, a heterocyclic compound having sulfuratom and/or oxygen atom in the ring structure and to form a protectivelayer on the surface of the anode electrode active material, thusimproving charge-discharge cycle characteristics (Patent Document 2).

Furthermore, for a non-aqueous liquid electrolyte secondary batterybased on various anode electrode material, a liquid electrolyte wasproposed to which various compounds are added in addition to itselectrolyte and main solvent, in order to improve such characteristicsas load characteristics, cycle characteristics, storage characteristicsand low-temperature characteristics.

For example, in order to suppress decomposition of liquid electrolyte ofa non-aqueous liquid electrolyte secondary battery based on graphiteanode electrode, a carbonate derivative having an unsaturated bond hasbeen proposed such as an liquid electrolyte containing vinylenecarbonate and its derivative (for example, Patent Document 3), or aliquid electrolyte containing ethylene carbonate derivative havingnon-conjugated unsaturated bond in its side chain (for example, PatentDocument 4).

In the liquid electrolyte containing these compounds, theabove-mentioned compounds are reduced and decomposed on the surface ofthe anode electrode and a protective layer is formed, which inhibitsexcessive decomposition of the liquid electrolyte. A halogen-containingcarbonate was also proposed for the same purpose (for example PatentDocument 5).

-   [Patent Document 1] Japanese Patent Application Laid-Open    Publication No. H11-176470-   [Patent Document 2] Japanese Patent Application Laid-Open    Publication No. 2004-87284-   [Patent Document 3] Japanese Patent Application Laid-Open    Publication No. H8-45545-   [Patent Document 4] Japanese Patent Application Laid-Open    Publication No. 2000-40526-   [Patent Document 5] Japanese Patent Application Laid-Open    Publication No. H11-195429

DISCLOSURE OF THE INVENTION Problem to Be Solved by the Invention

Previous secondary batteries described in Patent Documents 1 and 2 usean element such as Si as anode electrode material. Although highcapacity was thereby obtained, they were inadequate with respect toperformance on longer-term charge-discharge cycle and, especially,discharge capacity retention discharge capacity retention.

Technologies descried in Patent Documents 3 to 5 were also inadequatewith respect to cycle characteristics (discharge capacity retentiondischarge capacity retention). Therefore, further improvement in cyclecharacteristics (discharge capacity retention) is urgently needed fornon-aqueous liquid electrolyte secondary battery based on various anodeelectrode material.

The present invention has been made to solve the above problems.

Namely, a purpose of the present invention is to provide a non-aqueousliquid electrolyte secondary battery, having high charging capacity,capable of maintaining excellent characteristics over a long period oftime and excellent in cycle characteristics (discharge capacityretention) in particular, and a non-aqueous liquid electrolyte to beused for it, in a non-aqueous liquid electrolyte secondary battery basedon a anode electrode active material having at least one kind of atomselected from the group consisting of Si atom, Sn atom and Pb atom.

Another purpose of the present invention is to provide a non-aqueousliquid electrolyte secondary battery, having high charging capacity,capable of maintaining excellent characteristics over a long period oftime and excellent in cycle characteristics (discharge capacityretention) in particular, and a non-aqueous liquid electrolyte to beused for it, in a non-aqueous liquid electrolyte secondary battery whichuses various materials such as graphite as anode electrode activematerial.

Means for Solving the Problem

The present inventors made an extensive effort to solve the aboveproblems and have found that it is possible to solve the problems byincorporating in the non-aqueous liquid electrolyte a carbonate havingat least either an unsaturated bond or a halogen atom and at least onecomponent of (i) to (iii) described later (specific component), in anon-aqueous liquid electrolyte secondary battery based on a anodeelectrode active material having at least one kind of atom selected fromthe group consisting of Si atom, Sn atom and Pb atom. It was also foundthat component (i) and component (ii) are effective without beingcombined with the specific carbonate, and that the effect of component(iii) is not limited to the secondary battery which uses the abovespecific anode electrode active material but the same effect is alsoexhibited for the secondary battery based on various anode electrodeactive material such as graphite material. These findings led to thecompletion of the present invention.

One subject matter of the present invention is a non-aqueous liquidelectrolyte to be used for a non-aqueous liquid electrolyte secondarybattery comprising a anode electrode and a cathode electrode cathodeelectrode, capable of intercalating and deintercalating lithium ions,and the non-aqueous liquid electrolyte, the anode electrode containing aanode electrode active material having at least one kind of atomselected from the group consisting of Si atom, Sn atom and Pb atom,wherein said non-aqueous liquid electrolyte contains a carbonate havingat least either an unsaturated bond or a halogen atom, and also containsat least one of: (i) a compound represented by the general formula (I)below and a saturated cyclic carbonate compound; (ii) a compoundrepresented by the general formula (II) below; and (iii) a compoundrepresented by the general formula (III-1) below.

(In the above formula (I), n represents an integer which is greater thanor equal to 3, m represents an integer which is greater than or equal to1, and the sum of n and m is greater than or equal to 5. All or part ofthe hydrogen atoms may be substituted with a fluorine atom.)

(In the above formula (II), X represents a group represented by

and R¹ to R⁶ each represent, independently of each other, anunsubstituted alkyl group or halogen-substituted alkyl group.)

[Chemical Formula 5]

A-N═C═O  (III-1)

(In the above formula (III-1), A represents an element or group otherthan a hydrogen.)

It is preferable that, in the above general formula (I), n and m areintegers different from each other (Claim 2).

It is preferable that, in said non-aqueous liquid electrolyte, theconcentration of said compound represented by the general formula (I) is5 volume % or higher, and 95 volume % or lower (Claim 3).

It is preferable that, in said non-aqueous liquid electrolyte, theconcentration of said saturated cyclic carbonate is 5 volume % orhigher, and 50 volume % or lower (Claim 4).

It is preferable that, in the above general formula (II), R¹ to R⁶ eachrepresent, independently of each other, an unsubstituted orfluorine-substituted alkyl group having 1 to 3 carbon atoms (Claim 5).

It is preferable that, in said non-aqueous liquid electrolyte, theconcentration of said compound represented by the general formula (II)is 0.01 weight % or higher, and 10 weight % or lower (Claim 6).

It is preferable that said compound represented by the general formula(III-1) is a compound selected from the compounds represented by thegeneral formula (III-2) below (Claim 7).

(In the above general formula (III-2),

X¹ and X² represent, independently of each other, an element other thanhydrogen,Z represents an arbitrary element or group,m and n represent, independently of each other, an integer greater thanor equal to 1, andwhen m is 2 or greater, each of Z may be the same or different from eachother.)

It is preferable that said compound represented by the general formula(III-1) is a compound selected from the compounds represented by thegeneral formula (III-3) below (Claim 8).

(In the above general formula (III-3), R represents, independently ofeach other, an alkyl group or aryl group that may have a substituent. Inaddition, more than one R may be connected to each other to form aring.)

It is preferable that, in said non-aqueous liquid electrolyte, theconcentration of said compound represented by the general formula(III-1) is 0.01 weight % or higher, and 10 weight or lower (Claim 9).

It is preferable that, in said non-aqueous liquid electrolyte, theconcentration of said carbonate having at least either an unsaturatedbond or a halogen atom is 0.01 weight % or higher, and 70 weight % orlower (Claim 10).

It is preferable that said carbonate having an unsaturated bond or ahalogen atom is one or more carbonates selected from the groupconsisting of vinylene carbonate, vinylethylene carbonate,fluoroethylene carbonate, difluoroethylene carbonate and derivatives ofthese compounds (Claim 11).

It is preferable that it further comprises ethylene carbonate and/orpropylene carbonate (Claim 12).

It is preferable that it further comprises at least one additionalcarbonate selected from the group consisting of dimethyl carbonate,ethylmethyl carbonate, diethyl carbonate, methyl-n-propyl carbonate,ethyl-n-propyl carbonate and di-n-propyl carbonate (Claim 13).

Another subject matter of the present invention is a non-aqueous liquidelectrolyte to be used for a non-aqueous liquid electrolyte secondarybattery comprising a anode electrode and a cathode electrode cathodeelectrode, capable of intercalating and deintercalating lithium ions,and the non-aqueous liquid electrolyte, the anode electrode containing aanode electrode active material having at least one kind of atomselected from the group consisting of Si atom, Sn atom and Pb atom,wherein said non-aqueous liquid electrolyte contains a compoundrepresented by the general formula (I) below and a saturated cycliccarbonate (Claim 14).

(In the above formula (I),n represents an integer which is greater than or equal to 3, mrepresents an integer which is greater than or equal to 1, and the sumof n and m is greater than or equal to 5.All or part of the hydrogen atoms may be substituted with a fluorineatom.)

It is preferable that, in the above general formula (I), n and m areintegers different from each other (Claim 15).

It is preferable that, in said non-aqueous liquid electrolyte, theconcentration of said compound represented by the general formula (I) is5 volume % or higher, and 95 volume % or lower (Claim 16).

It is preferable that, in said non-aqueous liquid electrolyte, theconcentration of said saturated cyclic carbonate is 5 volume % orhigher, and 50 volume % or lower (Claim 17).

Still another subject matter of the present invention is a non-aqueousliquid electrolyte to be used for a non-aqueous liquid electrolytesecondary battery comprising a anode electrode and a cathode electrodecathode electrode, capable of intercalating and deintercalating lithiumions, and the non-aqueous liquid electrolyte, the anode electrodecontaining a anode electrode active material having at least one kind ofatom selected from the group consisting of Si atom, Sn atom and Pb atom,

wherein said non-aqueous liquid electrolyte contains at least a compoundrepresented by the general formula (II) below (Claim 18).

(In the above formula (II),X represents a group represented by

and R¹ to R⁶ each represent, independently of each other, anunsubstituted alkyl group or halogen-substituted alkyl group.)

It is preferable that, in the above general formula (II), R¹ to R⁶ eachrepresent, independently of each other, an unsubstituted orfluorine-substituted alkyl group having 1 to 3 carbon atoms (Claim 19).

It is preferable that, in said non-aqueous liquid electrolyte, theconcentration of said compound represented by the formula (II) is 0.01weight % or higher, and 10 weight % or lower (Claim 20).

Still another subject matter of the present invention is a non-aqueousliquid electrolyte secondary battery comprising a anode electrode and acathode electrode cathode electrode, capable of intercalating anddeintercalating lithium ions, and a non-aqueous liquid electrolyte, theanode electrode containing a anode electrode active material having atleast one kind of atom selected from the group consisting of Si atom, Snatom and Pb atom, wherein said non-aqueous liquid electrolyte is anon-aqueous liquid electrolyte defined in any one of claims 1 to 20(Claim 21).

Still another subject matter of the present invention is a non-aqueousliquid electrolyte to be used for a non-aqueous liquid electrolytesecondary battery comprising a anode electrode and a cathode electrodecathode electrode, capable of intercalating and deintercalating lithiumions, and the non-aqueous liquid electrolyte, wherein said non-aqueousliquid electrolyte contains, at least, a carbonate having at leasteither an unsaturated bond or a halogen atom, and a compound representedby the general formula (III-1) below (Claim 22).

[Chemical Formula 12]

A-N═C═O  (III-1)

(In the above formula (III-1), A represents an element or group otherthan a hydrogen.)

It is preferable that said compound represented by the general formula(III-1) is a compound selected from the group represented by the generalformula (III-2) below (Claim 23).

(In the above general formula (III-2),X¹ and X² represent, independently of each other, an element other thanhydrogen,Z represents an arbitrary element or group,m and n represent, independently of each other, an integer greater thanor equal to 1, andwhen m is 2 or greater, each of Z may be the same or different from eachother.)

It is preferable that said compound represented by the general formula(III-1) is a compound selected from the group represented by the generalformula (III-3) below (Claim 24).

(In the above general formula (III-3),R represents, independently of each other, an alkyl group or aryl groupthat may have a substituent. In addition, more than one R may beconnected to each other to form a ring.)

It is preferable that, in said non-aqueous liquid electrolyte, theconcentration of said compound represented by the general formula(III-1) is 0.01 weight % or higher, and 10 weight or lower (Claim 25).

Still another subject matter of the present invention is a non-aqueousliquid electrolyte secondary battery comprising a anode electrode and acathode electrode cathode electrode, capable of intercalating anddeintercalating lithium ions, and a non-aqueous liquid electrolyte,wherein said non-aqueous liquid electrolyte is a non-aqueous liquidelectrolyte defined in any one of claims 22 to 25 (Claim 26).

Advantageous Effects of the Invention

The non-aqueous liquid electrolyte secondary battery of the presentinvention has high charge capacity and maintains an excellent propertyover a long period. It is excellent especially in discharge capacityretention.

BEST MODES FOR CARRYING OUT THE INVENTION

The present invention will be explained in detail below. The explanationgiven below indicates one example of each aspect of the invention(representative example) and by no means restrictive. Any modificationscan be added thereto insofar as they do not depart from the scope of theinvention.

[I. First Non-Aqueous Liquid Electrolyte]

First, explanation will be given on the non-aqueous liquid electrolyterelated to the first subject of the present invention (hereafterreferred to as “first non-aqueous liquid electrolyte of the presentinvention” as appropriate).

The first non-aqueous liquid electrolyte of the present invention is thenon-aqueous liquid electrolyte to be used for a non-aqueous liquidelectrolyte secondary battery comprising a anode electrode and a cathodeelectrode, capable of intercalating and deintercalating lithium ions,and a non-aqueous liquid electrolyte, the anode electrode containing aanode electrode active material having at least one kind of the atomselected from the group consisting of Si atom, Sn atom and Pb atom.

The first non-aqueous liquid electrolyte of the present inventionusually comprises, as its main components, an electrolyte andnon-aqueous solvent to dissolve it, similarly to a non-aqueous liquidelectrolyte generally used. It further comprises at least one of thecomponents of (i) to (iii) described later (hereafter referred to as“specific component” as appropriate), and a carbonate having at leasteither an unsaturated bond or a halogen atom (hereafter referred to as“specific carbonate” as appropriate). It may contain other componentssuch as an additive.

In the following description, explanation will be given, first, on thespecific component and specific carbonate, followed by the electrolyteand the non-aqueous solvent. Other components will also be touched upon.

[I-1. Specific Component]

The specific component of the present invention is at least one of thecomponents of (i) to (iii) described below.

-   -   Component (i): a compound represented by the general formula (I)        described later and a saturated cyclic carbonate compound.    -   Component (ii): a compound represented by the general        formula (II) described later.    -   Component (iii): a compound represented by the general formula        (III-1) described later.

In the following description, an effort will be made to make theexplanation easier. When it is necessary to differentiate the firstnon-aqueous liquid electrolytes of the present invention containingcomponent (i), component (ii) and component (iii), they will be referredto as “non-aqueous liquid electrolyte (I)”, “non-aqueous liquidelectrolyte (II)” and “non-aqueous liquid electrolyte (III)”,respectively. When no differentiation is necessary, they will bereferred to simply as “first non-aqueous liquid electrolyte of thepresent invention”.

The first non-aqueous liquid electrolyte of the present invention maycontain any one of the components of (i) to (iii) singly, or may containtwo or more components in any combination and in any ratio. Therefore,when reference is made to “non-aqueous liquid electrolyte (I)”, it is tobe understood that it implies not only the solution containing component(i) alone but also the solution further containing component (ii) and/orcomponent (iii). The same applies to the other cases.

In the following, components (i) to (iii) will be explained.

<I-1-1. Component (i)>

Component (i) is a combination of a compound represented by the generalformula (I) described later (hereinafter abbreviated as “specificcompound (I)” as appropriate) and a saturated cyclic carbonate compound.

I-1-1a. Specific Compound (I):

Specific compound (I) is a linear carbonate linear carbonate representedby the general formula (I) below.

(In the above formula (I), n represents an integer which is greater thanor equal to 3, m represents an integer which is greater than or equal to1, and the sum of n and m is greater than or equal to 5. All or part ofthe hydrogen atoms may be substituted with a fluorine atom.)

In the general formula (I) above, the number of carbon atoms n in thegroup —C_(n)H_(2n+1) (hereafter referred to “first substituent” asappropriate) is usually 3 or more, and usually 6 or less, preferably 5or less. When n exceeds this upper limit, the viscosity of thenon-aqueous liquid electrolyte tends to increase.

When the number of carbon atoms n of the first substituent is 3 or more,chemical reactivity of the linear carbonate linear carbonate towardsanode electrode active material containing the above-mentioned metalelements becomes lower, leading to inhibition of cycle deterioration.This is the reason the number of carbon atoms n in the first substituentof the present invention is set to be 3 or more. Carbonates with smallmolecular weight are highly reactive chemically and cycle deteriorationis liable to occur as a result of a side reaction. Linear carbonatelinear carbonates having the first substituent whose n is 3 or more arehigh enough in molecular weight and the above difficulty is reduced.

Concrete examples of the first substituent are: n-propyl group, i-propylgroup, n-butyl group, t-butyl group, n-pentyl group, 1-methylbutylgroup, 2-methylbutyl group, 3-methylbutyl group, 1,2-dimethylpropylgroup, 1-ethylpropyl group, n-hexyl group, 1-methylpentyl group,2-methylpentyl group, 3-methylpentyl group, 4-methylpentyl group,1,2-dimethylbutyl group, 1,3-dimethylbutyl group, 2,3-dimethylbutylgroup, 2-ethylbutyl group and 3-ethylbutyl group.

Of these, preferable are n-propyl group, n-butyl group and n-hexylgroup.

On the other hand, in the general formula (I) above, the number ofcarbon atoms m of the group —C_(m)H_(2m+1) (hereafter referred to“second substituent” as appropriate) is usually 1 or more, and the sumof n and m is an integer which is usually 5 or more and preferably 9 orless, more preferably 7 or less. When the sum n+m is below this range,the chemical reactivity of the linear carbonate becomes high due to itssmall molecular weight and cycle deterioration tends to occur as aresult of a side reaction. If the sum n+m exceeds the upper limit, thesolute does not dissolve easily, making preparation of the liquidelectrolyte difficult.

Concrete examples of the second substituent are: methyl group, ethylgroup, n-propyl group, i-propyl group, n-butyl group, t-buty1 group,n-pentyl group, 1-methylbutyl group, 2-methylbutyl group, 3-methylbutylgroup, 1,2-dimethylpropyl group, 1-ethylpropyl group, n-hexyl group,1-methylpentyl group, 2-methylpentyl group, 3-methylpentyl group,4-methylpentyl group, 1,2-dimethylbutyl group, 1,3-dimethylbutyl group,2,3-dimethylbutyl group, 2-ethylbutyl group and 3-ethylbutyl group.

Of these, preferable are methyl group and ethyl group.

All or part of hydrogen atoms in the first substituent and/or secondsubstituent of specific compound (I) may be substituted with a fluorineatom. Because a fluorine atom is highly resistant against oxidation,they are preferable as substituent element. There is no speciallimitation on the number of substituted fluorine atoms in specificcompound (I). Preferably, it is 6 or less.

The molecular weight of the specific compound (I) is usually 132 orhigher and usually 188 or lower, preferably 160 or lower. If this upperlimit is exceeded, dissolution of the solute tends to be difficult.

Concrete examples of specific compound (I) are: di-n-propyl carbonate,diisopropyl carbonate, n-propylisopropyl carbonate, di-n-butylcarbonate, di-1-propyl carbonate, di-t-butyl carbonate, n-butyl-i-butylcarbonate, n-butyl-t-butyl carbonate, i-butyl-t-butyl carbonate,n-butylmethyl carbonate, i-butylmethyl carbonate, t-butylmethylcarbonate, ethyl-n-propyl carbonate, n-butylethyl carbonate,i-butylethyl carbonate, t-butylethyl carbonate, n-butyl-n-propylcarbonate, i-butyl-n-propyl carbonate, t-butyl-n-propyl carbonate,n-butyl-i-propyl carbonate, i-butyl-i-propyl carbonate andt-butyl-i-propyl carbonate.

Concrete examples of specific compound (I) of the linear carbonatestructure in which one or more hydrogen atoms are replaced by one ormore fluorine atoms are: 4-monofluorobutylmethyl carbonate,4,4-difluorobutylmethyl carbonate, 4,4,4-trifluorobutyl carbonate,methyl-3,3,4,4,4-pentafluorobutyl carbonate,2,2,3,3,4,4,4-heptafluorobutylmethyl carbonate, ethyl-3-monofluoropropylcarbonate, 3,3-difluoropropylethyl carbonate,ethyl-3,3,3-trifluoropropyl carbonate, ethyl-2,2,3,3,3-pentafluorocarbonate, 2-monofluoroethylpropyl carbonate, 2,2-difluoroethylpropylcarbonate, propyl-2,2,2-trifluoroethyl carbonate,2,2,2-trifluoroethyl-3,3,3-trifluoropropyl carbonate,3,3,3,2,2-pentafluoropropyl-2,2,2-trifluoroethyl carbonate,3-monofluoropropylpropyl carbonate, 3,3-difluoropropylpropyl carbonate,propyl-3,3,3-trifluoropropyl carbonate,3,3,3,2,2-pentafluoropropylpropyl carbonate, bis-2-monofluoropropylcarbonate, bis-2,2-difluoropropyl carbonate, bis-2,2,2-trifluoropropylcarbonate and bis-3,3,3,2,2-pentafluoropropyl carbonate.

In the general formula (I) above, it is preferable that the compound isan asymmetric carbonate with n and m being different integers. Of thosecompounds, preferable are methylbutyl carbonate, ethylpropyl carbonateand ethylbutyl carbonate from the standpoint of basic characteristics asliquid electrolyte such as viscosity and conductivity. Furthermore, fromthe standpoint of battery characteristics such as cycle characteristics,preferable are methylbutyl carbonate, ethylpropyl carbonate, ethylbutylcarbonate and dipropyl carbonate. Of these compounds, particularlypreferable are ethylpropyl carbonate, ethylbutyl carbonate and dipropylcarbonate.

Specific compound (I) can be used in the first non-aqueous liquidelectrolyte (I) either singly or as a combination of more than one kindin any combination and in any ratio.

The proportion of specific compound (I) in the first non-aqueous liquidelectrolyte (I) is usually 50 volume % or larger, preferably 60 volume %or larger, and usually 95 volume % or smaller, preferably 90 volume % orsmaller. When the proportion of specific compound (I) is too small,dissociation degree of a lithium salt tends to be lower and electricconductivity of the non-aqueous liquid electrolyte obtained also tendsto be lower. On the other hand, when the proportion of specific compound(I) is too large, the viscosity of the non-aqueous liquid electrolyteobtained tends to be high.

I-1-1b. Saturated Cyclic Carbonate:

Examples of saturated cyclic carbonates to be combined with the specificcompound (I) above include ethylene carbonate, propylene carbonate andbutylene carbonate. Any hydrogen atom in these cyclic carbonates may besubstituted with fluorine atom.

Examples of compounds derived from the above cyclic carbonates byreplacing one or more hydrogen atoms with one or more fluorine atomsare: fluoroethylene carbonate, chloroethylene carbonate,4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate,4,4-dichloroethylene carbonate, 4,5-dichloroethylene carbonate,4-fluoro-4-methylethylene carbonate, 4-chloro-4-methylethylenecarbonate, 4,5-difluoro-4-methylethylene carbonate,4,5-dichloro-4-methylethylene carbonate, 4-fluoro-5-methylethylenecarbonate, 4-chloro-5-methylethylene carbonate,4,4-difluoro-5-methylethylene carbonate, 4,4-dichloro-5-methylethylenecarbonate, 4-(fluoromethyl)-ethylene carbonate,4-(chloromethyl)-ethylene carbonate, 4-(difluoromethyl)-ethylenecarbonate, 4-(dichloromethyl)ethylene carbonate,4-(trifluoromethyl)-ethylene carbonate, 4-(trichloromethyl)-ethylenecarbonate, 4-(trifluoromethyl)-4-fluoroethylene carbonate,4-(chloromethyl)-4-chloroethylene carbonate,4-(fluoromethyl)-5-fluoroethylene carbonate,4-(chloromethyl)-5-chloroethylene carbonate,4-fluoro-4,5-dimethylethylene carbonate, 4-chloro-4,5-dimethylethylenecarbonate, 4,5-difluoro-4,5-dimethylethylene carbonate,4,5-dichloro-4,5-dimethylethylene carbonate,4,4-difluoro-5,5-dimethylethylene carbonate and4,4-dichloro-5,5-dimethylethylene carbonate.

Of these, preferable are ethylene carbonate, propylene carbonate,fluoroethylene carbonate, 4,4-difluoroethylene carbonate,4,5-difluoroethylene carbonate and 4-(fluoromethyl)-ethylene carbonate,because the solute can be dissolved easily due to their high dielectricconstant and improved cycle characteristics of the battery can beexpected.

These saturated cyclic carbonates can be used either singly or as acombination of more than one kind in any combination and in any ratio.

The proportion of the saturated cyclic carbonate in the non-aqueousliquid electrolyte (I) is usually 5 volume % or larger, preferably 10volume or larger, and usually 50 volume % or smaller, preferably 40volume % or smaller. When the proportion of the saturated cycliccarbonate is too small, dissolution of the solute tends to be difficult.On the other hand, when the proportion is too large, the viscosity ofthe non-aqueous liquid electrolyte obtained tends to be high.

I-1-1c. Composition Ratio of Specific Compound (I) and Saturated CyclicCarbonate

The non-aqueous liquid electrolyte (I) contains the linear carbonaterepresented by the general formula (I) (specific compound (I)),saturated cyclic carbonate and specific carbonate described later. Ofthese compounds, specific carbonate is added to the non-aqueous liquidelectrolyte (I) as an additive. Therefore, the composition ratio hererefers to the ratio of specific compound (I) and saturated cycliccarbonate (hereafter, in the explanation of non-aqueous liquidelectrolyte (I), these may sometimes be termed “non-aqueous solvent”collectively).

As preferable combination of the non-aqueous solvent in the non-aqueousliquid electrolyte (I) can be cited the following (a) and (b):

(a) Combination of the specific compound and the saturated cycliccarbonate.(b) Combination of the specific carbonate, the saturated cycliccarbonate and other linear carbonate described later as desirablenon-aqueous solvent.

As described previously, preferable content of specific compound (I) inthe non-aqueous liquid electrolyte (I) is usually 50 volume % or higher,preferably 60 volume % or higher, and usually 95 volume % or lower,preferably 90 volume % or lower. Preferable content of the saturatedcyclic carbonate in the non-aqueous liquid electrolyte (I) is usually 5volume % or higher, preferably 10 volume % or higher, and usually 50volume % or lower, preferably 40 volume % or lower. Even when otherlinear carbonate is also contained in the non-aqueous liquid electrolyte(I), volume ratio of specific compound (I) and the saturated cycliccarbonate is preferably 50:50 to 95:5, more preferably 60:40 to 90:10.When the ratio of the linear carbonate is too low, the viscosity of thenon-aqueous liquid electrolyte obtained increases. When the ratio is toohigh, dissociation degree of a lithium salt decreases and electricconductivity of the non-aqueous liquid electrolyte obtained may becomelow.

The volume ratio of the other linear carbonate to the sum of specificcarbonate (I) and the saturated cyclic carbonate is usually 30 volume %or lower, preferably 25 volume % or lower. Inclusion of the other linearcarbonate in the non-aqueous liquid electrolyte (I) is helpful in makinga solute easily soluble even when the solute is difficult to dissolvewith specific carbonate (I) and the saturated cyclic carbonate alone.However, when the ratio exceeds this above limit, cycle characteristicsmay deteriorate.

In the non-aqueous liquid electrolyte (I), particularly preferablecombination and its volume ratio of non-aqueous solvents, although theseare not intended to be exhaustive, are as described below.

(1) Ethylene carbonate (EC) and ethyl-n-propyl carbonate (EPC)

EC:EPC=10:90 to 40:60, more preferably 20:80 to 30:70

(2) EC and dipropyl carbonate (DPC)

EC:DPC=10:90 to 40:60, more preferably 20:80 to 30:70

(3) EC and ethyl-n-butyl carbonate (EBC)

EC:EBC=10:90 to 40:60, more preferably 20:80 to 30:70

(4) Fluoroethylene carbonate (FEC) and EC and ethyl-n-propyl carbonate(EPC)

FEC:EC:EPC=5:5:90 to 25:25:50, more preferably 10:10:80 to 20:20:60

(5) FEC and EPC

FEC:EPC=10:90 to 40:60, more preferably 20:80 to 30:70

(6) FEC and DPC

FEC:DPC=10:90 to 40:60, more preferably 20:80 to 30:70

(7) FEC and EBC

FEC:EPC=10:90 to 40:60, more preferably 20:80 to 30:70

In the combinations of (1) to (7) above, still another linear carbonatemay be added such as dimethyl carbonate (DMC), ethylmethylmethylcarbonate (EMC) and diethyl carbonate (DEC). Examples include thefollowing combination and volume ratio.

(8) EC and EPC and DEC

EC:EPC:DEC=10 to 40:40 to 80:10 to 30

(9) EC and DPC and DEC

EC:DPC:DEC=10 to 40:40 to 80:10 to 30

(10) FEC and EPC and DEC

FEC:EPC:DEC=10 to 40:40 to 80:10 to 30

(11) FEC and DPC and DEC

FEC:DPC:DEC=10 to 40:40 to 80:10 to 30

In the above examples of preferable combination, any hydrogen atom ofthe alkyl groups of EPC, DPC and EBC may be replaced by a fluorine atom.

In addition to the above combination, it is preferable that the specificcarbonate to be described later is added to the non-aqueous liquidelectrolyte (I) in the amount of usually 0.01 weight % or larger,preferably 0.1 weight % or larger, more preferably 0.3 weight % orlarger, and usually 50 weight % or smaller, preferably 40 weight % orsmaller, more preferably 30 weight % or smaller. The rationale of thisrange will be mentioned later.

-   -   I-1-1d. Others:

The charge-discharge cycle characteristics are improved in thenon-aqueous liquid electrolyte (I) containing the above-mentionedspecific linear carbonate (specific compound (I)), saturated cycliccarbonate and specific carbonate described later. The detailed reason isnot clear, but inferred as follows.

The reactivity of the specific compound (I) in the non-aqueous liquidelectrolyte (I) towards anode electrode active material containing metalelement mentioned above becomes low by the presence of alkyl group orfluoroalkyl group with 3 or more carbon atoms, leading to suppression ofa side reaction and inhibition of deterioration of cyclecharacteristics. The similar effect can be obtained when the totalnumber of carbon atoms of alkyl or fluoroalkyl groups of the linearcarbonate is 5 or more. Thus, under the condition where the sidereaction due to the linear carbonate is suppressed, an effectiveprotective layer is formed by the specific carbonate described later.Solubility of the electrolyte is enhanced by the saturated cycliccarbonate and improvement in charge-discharge cycle characteristicsfollows.

This advantageous effect of the present invention derived from thecombined use of the specific compound (I), saturated cyclic carbonateand specific carbonate described later is characteristic of the use ofanode electrode active material having at least one kind of atomselected from the group consisting of Si atom, Sn atom and Pb atom. Aswill be described later in [Example•Comparative Example I], improvementin long term charge-discharge cycle characteristics can not be realizedwhen carbon material is used as anode electrode active material.

<I-1-2. Component (ii)>

Component (ii) is a compound represented by the general formula (II)below (hereafter referred to as “specific compound (II)” asappropriate).

(In the above formula (II), X represents a group represented by

(This may be hereinafter described as “—SO₂—”.)or

(This May be Hereinafter Described as “—SO—”.)

, and R¹ to R⁶ each represent, independently of each other, anunsubstituted alkyl group or halogen-substituted alkyl group.)

In the general formula (II) above, X represents —SO₂— or —SO— above.When it represents —SO₂—, the compound is a sulfate ester, assuming asulfate structure. When it represents —SO—, the compound is a sulfiteester, assuming a sulfite structure.

In the general formula (II) above, R¹ to R⁶ each represent,independently of each other, an unsubstituted alkyl group orhalogen-substituted alkyl group. The number of carbon atoms of thisalkyl group is usually one or more and 6 or less, preferably 3 or less.If n is too large, the effect of specific compound (II) per unit weightis not significant, making the presence of the compound meaningless.

Concrete examples of alkyl group are: methyl group, ethyl group,n-propyl group, i-propyl group, n-butyl group, s-butyl group, i-butylgroup, t-butyl group, n-pentyl group, 1-methylbutyl group, 2-methylbutylgroup, 3-methylbutyl group, 1,2-dimethylpropyl group, 1-ethylpropylgroup, n-hexyl group, 1-methylpentyl group, 2-methylpentyl group,3-methylpentyl group, 4-methylpentyl group, 1,2-dimethylbutyl group,1,3-dimethylbutyl group, 2,3-dimethylbutyl group, 2-ethylbutyl group and3-ethylbutyl group.

Of these, preferable are methyl group, ethyl group and n-propyl group.

When R¹ to R⁶ are halogen-substituted alkyl groups, substitution may befor all the hydrogen atoms of the alkyl group or for part of thehydrogen atoms. Fluorine atom and chlorine atom are cited as halogenatom. Fluorine atom is preferable because of its high resistance againstoxidation. No particular limitation is imposed on the number ofsubstituted halogen atoms. Preferable is 6 or less, more preferable is 3or less, per one alkyl group.

Examples of halogen-substituted alkyl group, where halogen atom isfluorine atom, are: fluoromethyl group, 1-fluoroethyl group,2-fluoroethyl group, 1-fluoro-n-propyl group, 2-fluoro-n-propyl group,3-fluoro-n-propyl group, difluoromethyl group, 1,1-difluoroethyl group,1,2-difluoroethyl group, 2,2-difluoroethyl group, 1,1-difluoro-n-propylgroup, 1,2-difluoro-n-propyl group, 1,3-difluoro-n-propyl group,2,2-difluoro-n-propyl group, 2,3-difluoro-n-propyl group,3,3-difluoro-n-propyl group, trifluoromethyl group, 1,1,2-trifluoroethylgroup, 1,2,2-trifluoroethyl group, 2,2,2-trifluoroethyl group,1,1,2-trifluoro-n-propyl group, 1,2,2-trifluoro-n-propyl group,1,1,3-trifluoro-n-propyl group, 1,2,3-trifluoro-n-propyl group,1,3,3-trifluoro-n-propyl group, 2,2,3-trifluoro-n-propyl group,2,3,3-trifluoro-n-propyl group and 3,3,3-trifluoro-n-propyl group.

The groups derived from the above-mentioned groups by substituting anyfluorine atom with any other halogen atom can also be cited ashalogen-substituted alkyl groups.

Of these groups, preferable from the standpoint of stability and ease ofpreparation are fluoromethyl group, trifluoromethyl group, 2-fluoroethylgroup, 2,2-difluoroethyl group, 2,2,2-trifluoroethyl group,3-fluoro-n-propyl group and 3,3,3-trifluoro-n-propyl group.

In the general formula (II) above, R¹ to R⁶ may be either the same ordifferent from one another. From the standpoint of ease of preparation,it is preferable that they belong to the same group.

Accordingly, as concrete examples of specific compound (II) can becited: silicon-containing sulfate esters such asbis(trimethylsilyl)sulfate,bis{tris(fluoromethyl)silyl}sufate,bis(triethylsilyl)sulfate,bis{tris(2-fluoroethyl)}sulfate, bis{tris(2,2-difluoroethyl)}sulfate,bis{tris(2,2,2-trifluoroethyl)}sulfate,bis(tri-n-propyl)sulfate,bis{tris(3-fluoro-n-propyl)}sulfate andbis{tris(3,3,3-trifluoro-n-propyl)}sulfate; and silicon-containingsulfite esters such as bis(trimethylsilyl)sulfite,bis{tris(fluoromethyl)silyl}sulfite, bis(triethylsilyl)sulfite,bis{tris(2-fluoroethly)}sulfite, bis{tris(2,2-difluoroethyl)}sulfite,bis{tris(2,2,2-trifluoroethyl)}sulfite,bis(tri-n-propyl)sulfite,bis{tris(3-fluoro-n-propyl)}sulfite andbis{tris(3,3,3-trifluoro-n-propyl)}sulfite.

Of these compounds, preferable are those in which R¹ to R⁶ in thegeneral formula (II) are, independently of each other, an unsubstitutedor fluorine-substituted alkyl group with 1 to 3 carbon atoms. Concreteexamples are: bis(trimethylsilyl)sulfate, bis(triethylsilyl)sulfate,bis{tris(2-fluoroethyl)}sulfate, bis{tris(2,2,2-trifluoroethyl)}sulfate,bis(tri-n-propyl)sulfate, bis(trimethylsilyl)sulfite,bis(triethylsilyl)sulfite, bis{tris(2-fluoroethly)}sulfite,bis{tris(2,2,2-trifluoroethyl)}sulfite and bis(tri-n-propyl) sulfite.

For these compounds, it is preferable that R¹ to R⁶ are the same group.Furthermore, it is particularly preferable that, in the above formula(II), R¹ to R⁶ are the same group and they are an unsubstituted orfluorine-substituted alkyl group with 1 or 2 carbon atoms. From thestandpoint of ease of technical availability, unsubstituted alkyl groupswith 1 to 2 carbon atoms are particularly preferable.

There is no special limitation on the molecular weight of specificcompound (II), insofar as the advantage of the present invention is notsignificantly impaired. It is usually 100 or larger, preferably 110 orlarger. No upper limit is imposed, although from a practical standpointit is usually 400 or smaller, preferably 300 or smaller, as theviscosity increases with the molecular weight.

There is no special limitation on the method of producing specificcompound (II) and any known method can be selected and used.

Specific compound (II), explained above, may be used in the non-aqueousliquid electrolyte (II) either singly or as a mixture of more than onekind in any combination and in any ratio.

There is no special limitation on the proportion of specific compound(II) in the non-aqueous liquid electrolyte (II), insofar as theadvantage of the present invention is not significantly impaired. Theproportion is usually 0.01 weight % or larger, preferably 0.1 weight %or larger, and usually 10 weight % or smaller, preferably 5 weight % orsmaller. If the proportion of specific compound (II) is too small,adequate effect of improving the cycle characteristics of the secondarybattery are not guaranteed when the non-aqueous liquid electrolyte isused for the non-aqueous liquid electrolyte secondary battery. On theother hand, if the proportion of specific compound (II) is too large,chemical reactivity of the non-aqueous liquid electrolyte tends toincrease and battery characteristics of the non-aqueous liquidelectrolyte secondary battery obtained may deteriorate.

In the non-aqueous liquid electrolyte (II), there is no speciallimitation on the ratio of the specific compound (II) and specificcarbonate described later. Relative weight ratio expressed as “weight ofspecific compound (II)/weight of specific carbonate” is usually 0.0001or larger, preferably 0.001 or larger, more preferably 0.01 or larger,and usually 1000 or smaller, preferably 100 or smaller, more preferably10 or smaller. If the above relative weight ratio is either too large ortoo small, synergistic effect of the specific compound (II) and specificcarbonate may not be realized.

It is possible to improve the charge-discharge cycle characteristics ofthe non-aqueous liquid electrolyte secondary battery by using thenon-aqueous liquid electrolyte (II) containing the above-mentionedspecific compound (II) and the specific carbonate described later. Thedetailed reason is not clear, but inferred as follows. Namely, throughthe reaction of both specific compound (II) and specific carbonatecontained in the non-aqueous liquid electrolyte (II), an effectiveprotective layer is formed on the surface of the anode electrode activematerial, leading to the suppression of side reactions. Cycledeterioration is thus inhibited. Although detailed reason is not clear,coexistence of the specific compound (II) and the specific carbonate inthe liquid electrolyte contributes to the improvement of thecharacteristics of the protective layer in some way or other.

This advantageous effect of the present invention derived from thecombined use of the specific compound (II) and the specific carbonatedescribed later is characteristic of the use of anode electrode activematerial having at least one kind of atom selected from the groupconsisting of Si atom, Sn atom and Pb atom. As will be described laterin [Example Comparative Example II], improvement in long termcharge-discharge cycle characteristics can not be realized when carbonmaterial is used as anode electrode active material.

<I-1-3. Component (iii)>

Component (iii) is a compound represented by the general formula (III-1)below (hereinafter abbreviated as “specific compound (III)”, asappropriate).

[Chemical Formula 19]

A-N═C═C═O  (III-1)

In the formula (III-1) above, A represents an arbitrary element or groupother than hydrogen. From the standpoint of electrochemical stability,it is preferable that A is a group other than aryl group or other thangroup having aryl group as substituent. Namely, it is preferable that Ais an element or group other than aryl group and it is also preferablethat A is an element or group other than group having aryl group assubstituent.

Furthermore, from the standpoint of stability of specific compound (III)as organic material and stability of protective layer formed, A ispreferably halogen among various elements. Of various functional groups,A is preferably a chained or cyclic, saturated or unsaturated alkylgroup which may have a substituent.

Of specific compounds (III), preferable are those represented by thegeneral formula (III-2) or (III-3) below.

(In the above formula (III-2), X¹ and X² represent, independently ofeach other, an element other than hydrogen and Z represents an arbitraryelement or group. M and n represent, independently of each other, aninteger greater than or equal to 1. When m is 2 or greater, each of Zmay be the same or different from each other.)

(In the above formula (III-3), R represents, independently of eachother, an alkyl group or aryl group that may have a substituent. Inaddition, more than one R may be connected to each other to form aring.)

The formula (III-2) and (III-3) will be explained in further detailbelow.

In the formula (III-2), X¹ and X² represent, independently of eachother, an element other than hydrogen. Any element other than hydrogencan be X¹ and X², insofar as they are consistent with the chemicalstructure of (III-2). As concrete examples of preferable X¹ can be citedcarbon atom, sulfur atom and phosphor atom. As concrete examples ofpreferable X² can be cited oxygen atom and nitrogen atom.

In the formula (III-2), Z represents an arbitrary element or group.Preferable concrete examples of Z include an alkyl group. Of the alkylgroup, preferable are methyl group, ethyl group, fluoromethyl group,trifluoromethyl group, 2-fluoroethyl group and 2,2,2-trifluoroethylgroup. Particularly preferable are methyl group and ethyl group. When mis greater than or equal to 2, each of Z may be the same or differentfrom each other. Further, more than one Z may be connected to each otherto form a ring.

In the formula (III-2), m and n indicate an integer which is greaterthan or equal to 1. As concrete examples of preferable specificcompounds expressed in the formula (III-2) can be cited the followingcompounds. In the compounds shown below, each of R¹ represents,independently of each other, an alkyl group. As concrete examples of R¹,alkyl groups described as appropriate examples of Z in the formula(III-2) can be cited.

On the other hand, in the formula (III-3), R represents, independentlyof each other, an alkyl group or aryl group that may have a substituent.

When R is an alkyl group, concrete examples of R include methyl group,ethyl group, fluoromethyl group, trifluoromethyl group, 2-fluoroethylgroup and 2,2,2-trifluoroethyl group. Preferable are methyl group andethyl group.

In case R is an aryl group, concrete examples include phenyl group,o-tosyl group, m-tosyl group, p-tosyl group, o-fluorophenyl group,m-fluorophenyl group and p-fluorophenyl group.

Each R may be identical to or different from each other. More than one Rmay be connected with each other to form a ring.

Concrete examples of specific compound (III) include the following:

Specific compound (III) may be used in the non-aqueous liquidelectrolyte (III) either singly or as a mixture of more than one kind inany combination and in any ratio.

There is no special limitation on the molecular weight of specificcompound (III), insofar as the advantage of the present invention is notsignificantly impaired. It is usually 100 or larger. Although no upperlimit is imposed, it is usually 300 or smaller, preferably 200 orsmaller from a practical standpoint.

There is no special limitation on the proportion of the specificcompound (III) in the non-aqueous liquid electrolyte (III), insofar asthe advantage of the present invention is not significantly impaired.Usually, the proportion is 0.01 weight or larger, preferably 0.1 weight% or larger, and usually 10 weight % or smaller, preferably 5 weight %or smaller in the non-aqueous liquid electrolyte (III). In case theproportion is below the above-mentioned lower limit, adequate effect ofimproving cycle characteristics of the non-aqueous liquid electrolytesecondary battery obtained is not guaranteed when the non-aqueous liquidelectrolyte is used for the non-aqueous liquid electrolyte secondarybattery. In case the upper limit is exceeded, chemical reactivity of thenon-aqueous liquid electrolyte tends to increase and batterycharacteristics of the non-aqueous liquid electrolyte secondary batteryobtained may deteriorate.

There is no special limitation on the method of producing specificcompound (III) and any known method can be used.

In the non-aqueous liquid electrolyte (III), there is no speciallimitation on the ratio of specific compound (III) and the specificcarbonate described later. Relative weight ratio expressed as “weight ofspecific compound (III)/weight of specific carbonate” is usually 0.001or larger, preferably 0.01 or larger, more preferably 0.1 or larger, andusually 1000 or smaller, preferably 100 or smaller, more preferably 10or smaller. If the above relative ratio is too large or too small,synergistic effect by combined use of specific compound (III) and thespecific carbonate may not be realized.

It is possible to improve the charge-discharge cycle characteristics ofthe non-aqueous liquid electrolyte secondary battery by using thenon-aqueous liquid electrolyte (III) containing the above-mentionedspecific compound (III) and the specific carbonate described later. Thedetailed reason is not clear, but inferred as follows. Namely, throughthe reaction of both specific compound (III) and the specific carbonatecontained in the non-aqueous liquid electrolyte (III), an effectiveprotective layer is formed on the surface of the anode electrode activematerial, leading to the suppression of side reactions. Cycledeterioration is thus inhibited.

[I-2. Specific Carbonate]

The specific carbonate of the present invention indicates a carbonatehaving at least either an unsaturated bond or a halogen atom. Namely,specific carbonate of the present invention may contain only anunsaturated bond or only a halogen atom. It may also contain both anunsaturated bond and a halogen atom.

There is no special limitation on the kind of carbonate having anunsaturated bond (referred to “unsaturated carbonate” as appropriate),insofar as it is a carbonate having carbon-to-carbon unsaturated bondsuch as carbon-to-carbon double bond or carbon-to-carbon triple bond.Any known unsaturated carbonate can be used. A carbonate having anaromatic ring can also be regarded as carbonate having an unsaturatedbond.

As examples of the unsaturated carbonate can be cited vinylene carbonateand its derivatives, ethylene carbonate substituted by a substituenthaving an aromatic ring or carbon-to-carbon unsaturated bond and itsderivatives, phenyl carbonates, vinyl carbonates and allyl carbonates.

Concrete examples of vinylene carbonate and its derivatives are:vinylene carbonate, methylvinylene carbonate, 4,5-dimethylvinylenecarbonate, phenylvinylene carbonate and 4,5-diphenylvinylene carbonate.

Concrete examples of ethylene carbonate substituted by a substituentcontaining an aromatic ring or a carbon-to-carbon unsaturated bond andits derivatives are: vinylethylene carbonate, 4,5-divinylethylenecarbonate, phenylethylene carbonate and 4,5-diphenylethylene carbonate.

Concrete examples of phenyl carbonates are: diphenyl carbonate,ethylphenyl carbonate, methylphenyl carbonate and t-butylphenylcarbonate.

Concrete examples of vinyl carbonates are: divinyl carbonate andmethylvinyl carbonate.

Concrete examples of allyl carbonates are: diallyl carbonate andallylmethyl carbonate.

Of these unsaturated carbonate compounds, preferable as specificcarbonate are vinylene carbonate and its derivatives, and ethylenecarbonate substituted by a substituent having an aromatic ring orcarbon-to-carbon unsaturated bond and its derivatives. In particular,vinylene carbonate, 4,5-diphenylvinylene carbonate, 4,5-dimethylvinylenecarbonate and vinylethylene carbonate can be preferably used, as theyform a stable interface protective layer.

On the other hand, regarding a carbonate having a halogen atom(abbreviated as “halogenated carbonate” as appropriate), no speciallimitation exists on its kind insofar as it contains a halogen atom. Anyhalogenated carbonate can be used.

Concrete examples of halogen atoms are fluorine atom, chlorine atom,bromine atom and iodine atom. Of these, preferable are fluorine atom andchlorine atom. Fluorine atom is particularly preferable. There is nospecial limitation on the number of halogen atoms contained in thehalogenated carbonate insofar as it is one or more, and usually 6 orless, preferably 4 or less. When the halogenated carbonate contains morethan one halogen atoms, they can be identical to or different from eachother.

Examples of halogenated carbonate include ethylene carbonatederivatives, dimethyl carbonate derivatives, ethylmethyl carbonatederivatives and diethyl carbonate derivatives.

Concrete examples of ethylene carbonate derivatives are: fluoroethylenecarbonate, chloroethylene carbonate, 4,4-difluoroethylene carbonate,4,5-difluoroethylene carbonate, 4,4-dichloroethylene carbonate,4,5-dichloroethylene carbonate, 4-fluoro-4-methylethylene carbonate,4-chloro-4-methylethylene carbonate, 4,5-difluoro-4-methylethylenecarbonate, 4,5-dichloro-4-methylethylene carbonate,4-fluoro-5-methylethylene carbonate, 4-chloro-5-methylethylenecarbonate, 4,4-difluoro-5-methylethylene carbonate,4,4-dichloro-5-methylethylene carbonate, 4-(fluoromethyl)-ethylenecarbonate, 4-(chloromethyl)-ethylene carbonate,4-(difluoromethyl)-ethylene carbonate, 4-(dichloromethyl)-ethylenecarbonate, 4-(trifluoromethyl)-ethylene carbonate,4-(trichloromethyl)-ethylene carbonate,4-(fluoromethyl)-4-fluoroethylene carbonate,4-(chloromethyl)-4-chloroethylene carbonate,4-(fluoromethyl)-5-fluoroethylene carbonate,4-(chloromethyl)-5-chloroethylene carbonate,4-fluoro-4,5-dimethylethylene carbonate, 4-chloro-4,5-dimethylethylenecarbonate, 4,5-difluoro-4,5-dimethylethylene carbonate,4,5-dichloro-4,5-dimethylethylene carbonate,4,4-difluoro-5,5-dimethylethylene carbonate and4,4-dichloro-5,5-dimethylethylene carbonate.

Concrete examples of dimethyl carbonate derivatives are: fluoromethylmethyl carbonate, difluoromethyl methyl carbonate, trifluoromethylmethyl carbonate, bis(fluoromethyl)carbonate, bis(difluoro) methylcarbonate, bis(trifluoro) methyl carbonate, chloromethylmethylcarbonate, dichloroethylmethyl carbonate, trichloromethylmethylcarbonate, bis(chloromethyl)carbonate, bis(dichloro)methyl carbonate andbis(trichloro)methyl carbonate.

Concrete examples of ethylmethyl carbonate derivatives are:2-fluoroethylmethyl carbonate, ethylfluoromethyl carbonate,2,2-difluoroethylmethyl carbonate, 2-fluoroethylfluoromethyl carbonate,ethyldifluoromethyl carbonate, 2,2,2-trifluoroethylmethyl carbonate,2,2-difluoroethylfluoromethyl carbonate, 2-fluoroethyldifluoromethylcarbonate, ethyltrifluoromethyl carbonate, 2-chloroethylmethylcarbonate, ethylchloromethyl carbonate, 2,2-dichloroethylmethylcarbonate, 2-chloroethylchloromethyl carbonate, ethyldichloromethylcarbonate, 2,2,2-trichloroethylmethyl carbonate,2,2-dichloroethylchloromethyl carbonate, 2-chloroethyldichloromethylcarbonate and ethyltrichloromethyl carbonate.

Concrete examples of diethyl carbonate derivatives are:ethyl-(2-fluoroethyl) carbonate, ethyl-(2,2-difluoroethyl) carbonate,bis(2-fluoroethyl) carbonate, ethyl-(2,2,2-trifluoroethyl) carbonate,2,2-difluoroethyl-2′-fluoroethyl carbonate, bis(2,2-difluoroethyl)carbonate, 2,2,2-trifluoroethyl-2′-fluoroethyl carbonate,2,2,2-trifluoroethyl-2′,2′-difluoroethyl carbonate,bis(2,2,2-trifluoroethyl) carbonate, ethyl-(2-chloroethyl) carbonate,ethyl-(2,2-dichloroethyl) carbonate, bis(2-chloroethyl) carbonate,ethyl-(2,2,2-trichloroethyl) carbonate, 2,2-dichloroethyl-2′-chloroethylcarbonate, bis(2,2-dichloroethyl) carbonate,2,2,2-trichloroethyl-2′-chloroethyl carbonate,2,2,2-trichloroethyl-2′,2′-dichloroethyl carbonate andbis(2,2,2-trichloroethyl) carbonate.

Of these halogenated carbonates, preferable are carbonates containing afluorine atom. Particularly preferable are ethylene carbonatederivatives containing a fluorine atom. In particular, fluoroethylenecarbonate, 4-(fluoromethyl)-ethylene carbonate, 4,4-difluoroethylenecarbonate and 4,5-difluoroethylene carbonate can preferably be used, asthese compounds form an interface protective layer.

Furthermore, it is possible to use a carbonate containing both anunsaturated bond and a halogen atom (abbreviated as “halogenatedunsaturated carbonate” as appropriate) as specific carbonate. There isno special limitation on the halogenated unsaturated carbonate used andany such compounds can be used insofar as the advantage of the presentinvention is not significantly impaired.

Examples of halogenated, unsaturated carbonates include vinylenecarbonate derivatives, ethylene carbonate derivatives substituted by asubstituent having an aromatic ring or carbon-to-carbon unsaturatedbond, and allyl carbonates.

Concrete examples of vinylene carbonate derivatives are: fluorovinylenecarbonate, 4-fluoro-5-methylvinylene carbonate,4-fluoro-5-phenylvinylene carbonate, chlorovinylene carbonate,4-chloro-5-methylvinylene carbonate and 4-chloro-5-phenylvinylenecarbonate.

Concrete examples of ethylene carbonate derivatives which is substitutedby a substituent having an aromatic ring or carbon to carbon unsaturatedbond are: 4-fluoro-4-vinylethylene carbonate, 4-fluoro-5-vinylethylenecarbonate, 4,4-difluoro-4-vinylethylene carbonate,4,5-difluoro-4-vinylethylene carbonate, 4-chloro-5-vinylethylenecarbonate, 4,4-dichloro-4-vinylethylene carbonate,4,5-dichloro-4-vinylethylene carbonate, 4-fluoro-4,5-divinylethylenecarbonate, 4,5-difluoro-4,5-divinylethylene carbonate,4-chloro-4,5-divinylethylene carbonate, 4,5-dichloro-4,5-divinylethylenecarbonate, 4-fluoro-4-phenylethylene carbonate,4-fluoro-5-phenylethylene carbonate, 4,4-difluoro-5-phenylethylenecarbonate, 4,5-difluoro-4-phenylethylene carbonate,4-chloro-4-phenylethylene carbonate, 4-chloro-5-phenylethylenecarbonate, 4,4-dichloro-5-phenylethylene carbonate,4,5-dichloro-4-phenylethylene carbonate,4,5-difluoro-4,5-diphenylethylene carbonate and4,5-dichloro-4,5-diphenylethylene carbonate.

Concrete examples of phenyl carbonates are: fluoromethylphenylcarbonate, 2-fluoromethylphenyl carbonate, 2,2-difluoromethylphenylcarbonate, 2,2,2-trifluoromethylphenyl carbonate, chloromethylphenylcarbonate, 2-chloromethylphenyl carbonate, 2,2-dichloroethylphenylcarbonate and 2,2,2-trichloromethylphenyl carbonate.

Concrete examples of vinyl carbonates are: fluoromethylvinyl carbonate,2-fluoroethylvinyl carbonate, 2,2-difluoroethylvinyl carbonate,2,2,2-trifluoromethylvinyl carbonate, chloromethylvinyl carbonate,2-chloroethylvinyl carbonate, 2,2-dichloroethylvinyl carbonate and2,2,2-trichloroethylvinyl carbonate.

Concrete examples of allyl carbonates are: fluoromethylallyl carbonate,2-fluoroethylallyl carbonate, 2,2-difluoroethylallyl carbonate,2,2,2-trifluoroethylallyl carbonate, chloromethylallyl carbonate,2-chloroethylallyl carbonate, 2,2-dichloroethylallyl carbonate and2,2,2-trichloroethylallyl carbonate.

Of the halogenated unsaturated carbonates mentioned above, particularlypreferable as specific carbonate are one or more compounds selected fromthe group consisting of vinylene carbonate, vinylethylene carbonate,fluoroethylene carbonate, 4,5-difluoroethylene carbonate, andderivatives of these carbonate compounds, which are highly effectivewhen used alone.

There is no special limitation on the molecular weight of the specificcarbonate, insofar as the advantage of the present invention is notsignificantly impaired. It is usually 50 or larger, preferably 80 orlarger, and usually 250 or smaller, preferably 150 or smaller. When itis too large, the solubility of the specific carbonate in thenon-aqueous liquid electrolyte decreases and the advantageous effect ofthe present invention may not be adequately realized.

There is no special limitation on the method of producing the specificcarbonate and any known method can be selected and used.

The specific carbonate, explained above, may be used in the firstnon-aqueous liquid electrolyte of the present invention either singly oras a mixture of more than one kind in any combination and in any ratio.

There is no special limitation on the proportion of the specificcarbonate in the first non-aqueous liquid electrolyte of the presentinvention, insofar as the advantage of the present invention is notsignificantly impaired. The proportion is usually 0.01 weight or larger,preferably 0.1 weight or larger, more preferably 0.3 weight % or larger,and usually 70 weight or smaller, preferably 50 weight % or smaller,more preferably 40 weight or smaller. If the proportion is below theabove-mentioned lower limit, adequate effect of improving cyclecharacteristics of the non-aqueous liquid electrolyte secondary batteryare not guaranteed when the first non-aqueous liquid electrolyte of thepresent invention is used for the non-aqueous liquid electrolytesecondary battery. If the upper limit is exceeded, high-temperaturestorage characteristics and trickle charging characteristics of thenon-aqueous liquid electrolyte secondary battery tend to deteriorate,leading to increased gas evolution and deterioration of dischargecapacity retention, when the first non-aqueous liquid electrolyte of thepresent invention is used for the non-aqueous liquid electrolytesecondary battery.

In the non-aqueous liquid electrolyte (I), specific compound (I) and/orthe saturated cyclic carbonate, mentioned above, may be a carbonatehaving an unsaturated bond and/or a halogen atom. In those cases, thatspecific compound (I) and/or saturated cyclic carbonate can functionalso as the specific carbonate, and use of additional specific carbonateis not necessary.

[I-3. Non-Aqueous Solvent]

As non-aqueous solvent contained in the first non-aqueous liquidelectrolyte of the present invention, any such solvent can be used,insofar as the advantageous effect of the present invention is notsignificantly impaired. Non-aqueous solvent may be used either singly oras a combination of more than one kind in any combination and in anyratio.

Examples of usually used non-aqueous solvent include: cyclic carbonate,linear carbonate, chained and cyclic carboxylic acid ester, chained andcyclic ether, phosphor-containing organic solvent and sulfur-containingorganic solvent.

There is no special limitation on the kind of the cyclic carbonate.Examples of those usually used, except the specific carbonates mentionedpreviously, include: ethylene carbonate, propylene carbonate andbutylene carbonate.

Of these compounds, ethylene carbonate and propylene carbonate arepreferable because they have high dielectric constant, which effectseasy dissolution of the solute, and assures good cycle characteristicswhen used for the non-aqueous electrolyte solution secondary battery.Accordingly, it is preferable that the first non-aqueous liquidelectrolyte of the present invention contains, as non-aqueous solvent,ethylene carbonate and/or propylene carbonate, in addition to thespecific carbonate mentioned before.

There is no special limitation on the kind of the linear carbonate,either. Examples of those usually used, except the specific carbonatesmentioned previously, include: dimethyl carbonate, ethylmethylcarbonate, diethyl carbonate, methyl-n-propyl carbonate, ethyl-n-propylcarbonate and di-n-propyl carbonate.

Therefore, it is preferable that the first non-aqueous liquidelectrolyte of the present invention contains, as non-aqueous solvent,at least one carbonate selected from the group consisting of dimethylcarbonate, ethylmethyl carbonate, diethyl carbonate, methyl-n-propylcarbonate, ethyl-n-propyl carbonate and di-n-propyl carbonate, inaddition to the specific carbonate mentioned before. Of these, diethylcarbonate, methyl-n-propyl carbonate and ethyl-n-propyl carbonate arepreferable, and diethyl carbonate is particularly preferable because ofits excellent cycle characteristics when used for the non-aqueous liquidelectrolyte secondary battery.

There is no special limitation on the kind of the chained carboxylicacid ester. Examples of those usually used include: methyl acetate,ethyl acetate, n-propyl acetate, i-propyl acetate, n-butyl acetate,i-butyl acetate, t-butyl acetate, methyl propionate, ethyl propionate,n-propyl propionate, i-propyl propionate, n-butyl propionate, i-butylpropionate and t-butyl propionate.

Of these compounds, preferable are ethyl acetate, methyl propionate andethyl propionate.

There is no special limitation on the kind of cyclic carboxylic acidester. Examples of those usually used include: γ-butyrolactone,γ-valerolactone and δ-valerolactone.

Of these, γ-butyrolactone is preferable.

There is no special limitation on the kind of the chained ether.Examples of those usually used include: dimethoxymethane,dimethoxyethane, diethoxymethane, diethoxyethane, ethoxymethoxymethaneand ethoxymethoxymethane.

Of these, dimethoxyethane and diethoxyethane are preferable.

There is no special limitation on the kind of the cyclic ether. Examplesof those usually used include: tetrahydrofuran and2-methyltetrahydrofuran.

There is no special limitation on the kind of the phosphor-containingorganic solvent. Examples of those usually used include: phosphoric acidesters such as trimethyl phosphate, triethyl phosphate and triphenylphosphate; phosphinic acid esters such as trimethyl phosphite, triethylphosphite and triphenyl phosphite; and phosphine oxides such astrimethyl phosphine oxide, triethylphosphine oxide andtriphenylphosphine oxide.

There is no special limitation on the kind of the sulfur-containingorganic solvent. Examples of those usually used include: ethylenesulfite, 1,3-propane sultone, 1,4-butane sultone, methyl methanesulfonate, busulfan, sulfolane, sulforene, dimethyl sulfone, diphenylsulfone, methyl phenyl sulfone, dibutyl disulfide, dicyclohexyldisulfide, tetramethyl thiuram monosulfide, N,N-dimethylmethanesulfonamide and N,N-diethylethane sulfonamide.

Of these compounds, it is preferable to use ethylene carbonate and/orpropylene carbonate, which belongs to cyclic carbonate. It is furtherpreferable to combine the linear carbonate with these cyclic carbonates.

When the cyclic carbonate and linear carbonate are used in combinationas non-aqueous solvent, preferable content of the linear carbonate inthe non-aqueous solvent of the first non-aqueous liquid electrolyte ofthe present invention is usually 30 weight % or higher, preferably 50eight % or higher, and usually 95 weight % or lower, preferably 90 eight% or lower. On the other hand, preferable content of the cycliccarbonate in the non-aqueous solvent of the first non-aqueous liquidelectrolyte of the present invention is usually 5 weight % or higher,preferably 10 weight % or higher, and usually 50 weight % or lower,preferably 40 weight % or lower. When the content of the linearcarbonate is too low, the viscosity of the first non-aqueous liquidelectrolyte of the present invention may increase. When the content istoo high, dissociation degree of electrolyte lithium salt becomes low,leading to a decrease in electric conductivity of the first non-aqueousliquid electrolyte of the present invention.

In the non-aqueous liquid electrolyte (I), the saturated cycliccarbonate functions as non-aqueous solvent. Therefore, other non-aqueoussolvent may be added to the above specific compound (I) and saturatedcyclic carbonate but this is not necessary. When other non-aqueoussolvent is combined, the total amount of the saturated cyclic carbonateand other non-aqueous solvent should preferably fall within the rangespecified above for the non-aqueous solvent.

[I-4. Electrolyte]

There is no special limitation on the kind of electrolyte used for thefirst non-aqueous liquid electrolyte of the present invention. Anyelectrolyte known to be used as electrolyte of the intended non-aqueousliquid electrolyte secondary battery can be used. When the firstnon-aqueous liquid electrolyte of the present invention is used for thelithium secondary battery, a lithium salt is usually used aselectrolyte.

Concrete examples of electrolytes include: inorganic lithium salts suchas LiClO₄, LiAsF₆, LiPF₆, Li₂CO₃, and LiBF₄; fluorine-containing organiclithium salt such as LiCF₃SO₃, LiN(CF₃SO₂)₂, LiN(C₂F₆SO₂)₂, lithium1,3-hexafluoropropane disulfonylimide, lithium 1,2-tetrafluoroethanedisulfonylimide, LiN(CF₃SO₂)(C₄F₉SO₂), LiC(CF₃SO₂)₃, LiPF₄ (CF₃)₂, LiPF₄(C₂F₅)₂, LiPF₄(CF₃SO₂)₂, LiPF₄(C₂F₅SO₂)₂, LiBF₂(CF₃)₂, LiBF₂(C₂F₅)₂,LiBF₂(CF₃SO₂)₂ and LiBF₂(C₂F₅SO₂)₂; dicarboxylic acid-containing lithiumsalt complexes such as lithium bis(oxalato)borate, lithiumtris(oxalato)phosphate and lithium difluorooxalatoborate; and sodiumsalts and potassium salts such as KPF₆, NaPF₆, NaBF₄ and NaCF₃SO₃.

Of these, preferable are LiPF₆, LiBF₄, LiCF₃SO₃, LiN(CF₃SO₂)₂,LiN(C₂F₆SO₂)₂ and lithium 1,2-tetrafluoroethane disulfonylimide.Particularly preferable are LiPF₆ and LiBF₄.

The electrolyte can be used either singly or as a mixture of more thanone kind in any combination and in any ratio. In particular, when twospecific inorganic lithium salts are combined, or inorganic lithium saltand fluorine-containing organic lithium salt are combined, gas evolutionat the time of trickle charging is suppressed or deterioration at thetime of high temperature storage is suppressed, which is desirable.Particularly preferable are the combination of LiPF₆ and LiBF₄, or thecombination of inorganic lithium salt, such as LiPF₆ and/or LiBF₄, andfluorine-containing organic lithium salt, such as LiCF₃SO₃, LiN(CF₃SO₂)₂and LiN(C₂F₅SO₂)₂.

When LiPF₆ and LiBF₄ are combined, it is preferable that the ratio ofLiBF₄ in the whole electrolyte is usually 0.01 weight % or higher and 20weight or lower. Dissociation of LiBF₄ is not extensive and if the ratiois too high, resistance of the liquid electrolyte may become high.

When inorganic lithium salt such as LiPF₆ and LiBF₄ andfluorine-containing organic lithium salt such as LiCF₃SO₃, LiN(CF₃SO₂)₂and LiN(C₂F₅SO₂)₂ are used in combination, it is preferable that theratio of inorganic lithium salt in the whole electrolyte is usually 70weight % or higher, and 99 weight % or lower. The molecular weight offluorine-containing organic lithium salt is generally higher than thatof inorganic lithium salt. Therefore, when that ratio is too high, theratio of solvent in the liquid electrolyte decreases, resulting in highresistance of the liquid electrolyte.

No particular limitation is imposed on the concentration of the lithiumsalt in the first non-aqueous liquid electrolyte of the presentinvention, insofar as the advantage of the present invention is notsignificantly impaired. It is usually 0.5 mol·dm⁻³ or higher, preferably0.6 mol·dm⁻³ or higher, more preferably 0.8 mol·dm⁻³ or higher, andusually 3 mol·dm⁻³ or lower, preferably 2 mol·dm⁻³ or lower, morepreferably 1.5 mol·dm⁻³ or lower. When the concentration is too low, theelectric conductivity of the non-aqueous liquid electrolyte may beinadequate. When the concentration is too high, the electricconductivity decreases due to high viscosity, resulting in lowperformance of the non-aqueous electrolyte secondary battery based onthe first non-aqueous liquid electrolyte of the present invention.

[I-5. Additive]

It is preferable that the first non-aqueous liquid electrolyte ofpresent invention contains various additives to the extent that theadvantage of the present invention is not significantly impaired. As theadditive, any known ones can be used. The additive can be used eithersingly or as a mixture of more than one kind in any combination and inany ratio.

Examples of additives include overcharge-preventing agent and auxiliaryagent used to improve capacity retention characteristics and cyclecharacteristics after the high temperature storage.

Concrete examples of overcharge-preventing additives are: aromaticcompound such as biphenyl, alkyl biphenyl, terphenyl, partiallyhydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene,t-amylbenzene, diphenylether and dibenzofuran; partially fluorinatedabove aromatic compound such as 2-fluorobiphenyl,o-cyclohexylfluorobenzene and p-cyclohexylfluorobenzene;fluorine-containing anisole compound such as 2,4-difluoroanisole,2,5-difluoroanisole and 2,6-difluoroanisole.

These overcharge-preventing additives can be used either singly or as amixture of more than one kind in any combination and in any ratio.

When the first non-aqueous liquid electrolyte of the present inventioncontains overcharge-preventing additive, no particular limitation isimposed on its concentration used, insofar as the advantage of thepresent invention is not significantly impaired. Its content in thenon-aqueous liquid electrolyte is preferably 0.1 weight % or higher, and5 weight or lower. By incorporating the overcharge-preventing additivein the non-aqueous liquid electrolyte, it is possible to prevent ruptureand ignition caused by overcharge of the non-aqueous liquid electrolytesecondary battery, which preferably contributes to the enhancement ofsafety of the non-aqueous liquid electrolyte secondary battery.

On the other hand, concrete examples of auxiliary agent used to improvecapacity retention characteristics and cycle characteristics after thehigh temperature storage are: anhydrides of dicarboxylic acid such assuccinic acid, maleic acid and phthalic acid; carbonate compounds exceptthose designated as specific carbonates, such as erystan carbonate andspiro-bis-dimethylene carbonate; sulfur-containing compounds such asethylene sulfite, 1,3-propane sultone, 1,4-butane sultone, methylmethanesulfonate, busulfan, sulfurane, sulforene, dimethyl sulfone,diphenyl sulfone, methylphenyl sulfone, dibutyl disulfide, dicyclohexyldisulfide, tetramethylthiuram monosulfide, N,N-dimethylmethanesulfonamide and N,N-dimethylmethane sulfonamide; nitrogen-containingcompounds such as 1-methyl-2-pyrrolidinone, 1-methyl-2-piperidone,3-methyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone andN-methylsuccinimide; hydrocarbon compounds such as heptane, octane andcycloheptane; and fluorine-containing aromatic compounds such asfluorobenzene, difluorobenzene and benzotrifluoride.

These auxiliary agents can be used either singly or as a mixture of morethan one kind in any combination and in any ratio.

When the first non-aqueous liquid electrolyte of the present inventioncontains the auxiliary agent, no limitation is imposed on itsconcentration, insofar as the advantage of the present invention is notsignificantly impaired. Usually, it is preferable that its concentrationin the entire non-aqueous liquid electrolyte is 0.1 weight 1 or higherand 5 weight 1 or lower.

[II. First Non-Aqueous Liquid Electrolyte Secondary Battery]

Next, explanation will be given on the non-aqueous liquid electrolytesecondary battery, based on the first non-aqueous liquid electrolyte ofthe present invention (hereafter abbreviated as “first non-aqueousliquid electrolyte secondary battery of the present invention”)mentioned above. The first non-aqueous liquid electrolyte secondarybattery of the present invention comprises a anode electrode and acathode electrode, capable of intercalating and deintercalating lithiumions, and a non-aqueous liquid electrolyte, the anode electrodecontaining a anode electrode active material having at least one kind ofatom selected from the group consisting of Si atom, Sn atom and Pb atom,wherein said non-aqueous liquid electrolyte is the first non-aqueousliquid electrolyte of the present invention mentioned above.

[II-1. Constitution of Battery]

Constitution of the first non-aqueous liquid electrolyte secondarybattery of the present invention is similar to that of the knownnon-aqueous liquid electrolyte secondary battery except the constitutionof the anode electrode and non-aqueous liquid electrolyte. Usually, thecathode electrode and anode electrode are layered with a porous membrane(a separator) interposed therein, which is impregnated with the firstnon-aqueous liquid electrolyte of the present invention, and the wholestructure is stored in a case (an outer package). There is no speciallimitation on the shape of the first non-aqueous liquid electrolytesecondary battery of the present invention. The shape may becylindrical, prismatic, laminated, coin-like or large size-type.

[II-2. Non-Aqueous Liquid Electrolyte]

As non-aqueous liquid electrolyte, the first non-aqueous liquidelectrolyte of the present invention, described above, is used. Othernon-aqueous liquid electrolyte can be added to the first non-aqueousliquid electrolyte of the present invention to such an extent that itdoes not depart from the scope of the present invention.

[II-3. Anode Electrode]

The anode electrode of the first non-aqueous liquid electrolytesecondary battery of the present invention comprises anode electrodeactive material having at least one kind of atom selected from the groupconsisting of Si atom, Sn atom and Pb atom (hereafter referred to as“specific metal element” as appropriate).

As examples of anode electrode active material containing at least oneelement selected from the specific metal elements can be cited: any onespecific metal element alone; alloys consisting of two or more kinds ofthe specific metal elements; alloys consisting of one or more of thespecific metal elements and one or more other metal elements; andcompounds containing one or more of the specific metal elements. It ispossible to realize higher capacity of the battery by using these metalelements, alloys or metal compounds as anode electrode active material.

As examples of compounds containing one or more of the specific metalelements can be cited complex compounds, such as carbide, oxide,nitride, sulfide and phosphide, containing one or more of the specificmetal elements.

Also cited are compounds in which these complex compounds are furtherconnected to other metal elements, alloys or several elements such asnon-metal elements in a complicated manner. More concrete examples arealloys of Si or Sn with a metal not reacting as anode electrode. Alsousable are complex compounds containing 5 or 6 elements, in which Sn,for example, is combined with a metal which is other than Si, Sn and Pband is capable of acting as anode electrode, a metal not reacting asanode electrode and a non-metal element.

Of these anode electrode active materials, preferable are: any one kindof the specific metal elements used alone, alloys of two or more kindsof the specific metal elements, and oxides, carbides or nitrides of thespecific metal elements, as they have large capacity per unit weightwhen made into the battery. Particularly preferable are metal elements,alloys, oxides, carbides and nitrides of Si and/or Sn, from thestandpoint of capacity per unit weight and small burden on theenvironment.

Also preferable are the following Si and/or Sn-containing compoundsbecause of their excellent cycle characteristics, although they areinferior to metal alone or alloy in capacity per unit weight.

-   -   Oxides of Si and/or Sn in which the ratio of Si and/or Sn and        oxygen is usually 0.5 to 1.5, preferably 0.7 to 1.3, more        preferably 0.9 to 1.1.    -   Nitrides of Si and/or Sn in which the ratio of Si and/or Sn and        nitrogen is usually 0.5 to 1.5, preferably 0.7 to 1.3, more        preferably 0.9 to 1.1.    -   Carbides of Si and/or Sn in which the ratio of Si and/or Sn and        carbon is usually 0.5 to 1.5, preferably 0.7 to 1.3, more        preferably 0.9 to 1.1.

The above anode electrode active material can be used either singly oras a mixture of more than one kind in any combination and in any ratio.

The anode electrode of the first non-aqueous liquid electrolytesecondary battery of the present invention can be produced according toa known method. Specifically, the anode electrode can be produced usingthe above-mentioned anode electrode active material combined withbinder, electroconductor or the like, directly by roll-molding into asheet electrode, or by compression-molding into a pellet electrode, forexample. However, it is usually produced by forming a thin layercontaining the above anode electrode active material (anode electrodeactive material layer) on a current collector for a anode electrode(hereinafter, referred to as “anode electrode current collector” asappropriate) by means of coating, vapor deposition, spattering, platingor the like. In this case, the above anode electrode active material ismixed with, for example, binder, thickener, electroconductor, solvent orthe like to be made into the form of slurry. Then the slurry is appliedto the anode electrode current collector, dried and pressed to increaseits density, thereby the anode electrode active material layer beingformed on the anode electrode current collector.

As materials of anode electrode current collector can be cited steel,copper alloy, nickel, nickel alloy and stainless steel. Of thesematerials, preferable is copper foil, because of its thin-layerformability and low cost.

The thickness of the anode electrode current collector is usually 1 μmor greater, preferably 5 μm or greater, and usually 100 μm or less,preferably 50 μm or less. When the anode electrode current collector istoo thick, the capacity of the entire battery may become too low. On theother hand, when it is too thin, its handling is sometimes difficult.

In order to increase the bindability of the anode electrode currentcollector to the anode electrode active material layer formed thereon,it is preferable that the surface of the anode electrode currentcollector is subjected to roughening procedure in advance. Examples ofsurface roughening methods include: blasting procedure; rolling with arough-surfaced roll; mechanical polishing in which the collector surfaceis polished with such means as an abrasive cloth or abrasive paper ontowhich abradant particles are adhered, a whetstone, an emery buff and awire brush equipped with steel wire; electropolishing; and chemicalpolishing.

In order to decrease the weight of the anode electrode current collectorand increase energy density of the battery per unit weight, it is alsopossible to use a perforated-type anode electrode current collectorssuch as an expanded metal or a punching metal. This type of anodeelectrode current collector is freely adjustable in its weight by meansof adjusting its ratio of perforation. Besides, when the anode electrodeactive material layer is formed on both sides of this perforated-type ofanode electrode current collector, the anode electrode active materiallayer is riveted at these perforations and becomes resistant toexfoliation of the anode electrode active material layer. However, ifthe ratio of perforation is too high, bond strength may rather decreasebecause the contact area between the anode electrode active materiallayer and the anode electrode current collector becomes too small.

Slurry for making the anode electrode active material layer is usuallyprepared by adding such agents as binder and thickener to the anodeelectrode material. Incidentally, in this specification, the term “anodeelectrode material” indicates a material containing both anode electrodeactive material and electroconductor.

The content of the anode electrode active material in the anodeelectrode material is usually 70 weight % or higher, preferably 75weight % or higher, and usually 97 weight % or lower, preferably 95weight % or lower. When the content of the anode electrode activematerial is too low, the capacity of the secondary battery based on theanode electrode obtained tends to be insufficient. When the content istoo high, the relative content of the binder etc. becomes low, leadingto insufficient strength of the anode electrode. When two or more kindsof anode electrode active materials are combined, the sum of thematerials should fall within the above range.

As electroconductor to be used for the anode electrode can be citedmetal material such as copper and nickel, and carbon materials such asgraphite and carbon black. These materials can be used either singly oras a mixture of more than one kind in any combination and in any ratio.Carbon material can be advantageously used as electroconductor, as thismaterial can also function as active material. The content of theelectroconductor in the anode electrode material is usually 3 weight %or higher, preferably 5 weight % or higher, and usually 30 weight % orlower, preferably 25 weight % or lower. When the content of theelectroconductor is too low, conductivity may be inadequate. When it istoo high, the relative content of the anode electrode active materialmay be inadequate, leading to a decrease in battery capacity andmechanical strength. When two or more electroconductors are combined,the total content of the electroconductors should be adjusted to fallwithin the above range.

As binder to be used for the anode electrode, any such material can beused insofar as it is stable in a solvent used for electrode productionand in a liquid electrolyte. As examples can be cited polyfluorinatedvinylidene, polytetrafluoro ethylene, polyethylene, polypropylene,styrene butadiene rubber, isoprene rubber, butadiene rubber, ethyleneacrylic acid copolymer and ethylene methacrylic acid copolymer. Thesebinders can be used either singly or as a mixture of more than one kindin any combination and in any ratio. The content of the binder per 100weight parts of the anode electrode material is usually 0.5 weight partor more, preferably 1 weight part or more, and usually 10 weight partsor less, preferably 8 weight parts or less. When the content of thebinder is too small, mechanical strength of the anode electrode obtainedtends to be insufficient. When the content is too high, the relativecontent of the anode electrode active material is low, leading possiblyto insufficient battery capacity and conductivity. When two or morebinders are combined, the total content of the binders should beadjusted to fall within the above range.

As thickener to be used for the anode electrode can be citedcarboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose,ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylatedstarch and casein. These may be used either singly or as a mixture ofmore than one kind in any combination and in any ratio. The thickenermay be used when considered necessary. When it is used, it is preferablethat its content in the anode electrode active material is usually heldat 0.5 weight % or higher, and 5 weight % or lower.

Slurry for making the anode electrode active material layer is usuallyprepared by mixing, as needed, electroconductor, binder or thickenerwith the above anode electrode active material, using aqueous solvent ororganic solvent as dispersion medium. As aqueous solvent, water isusually used. It is also possible to mix other solvent, e.g. alcoholsuch as ethanol or cyclic amide such as N-methylpyrrolidone, in a rationot exceeding about 30 weight % relative to water. Examples of organicsolvent usually used include: cyclic amides such as N-methylpyrrolidone;straight chain amides such as N,N-dimethylformamide andN,N-dimethylacetamide; aromatic hydrocarbons such as anisole, tolueneand xylene; and alcohols such as butanol and cyclohexanol. Of these,preferable are cyclic amides, such as N-methylpyrrolidone, and straightchain amides, such as N,N-dimethylformamide and N,N-dimethylacetamide.These solvents can be used either singly or as a mixture of more thanone kind in any combination and in any ratio.

No particular limitation is imposed on the viscosity of the slurry,insofar as the slurry can be applied on the current collector. Theamount of the solvent used at the time of slurry preparation can beadjusted appropriately to give a suitable viscosity for application.

Slurry obtained is applied on the above anode electrode currentcollector, and after drying and pressing, anode electrode activematerial layer is formed. No particular limitation is imposed on themethod of application and known methods can be used. No particularlimitation is imposed on the method of drying either, and per se knownmethods such as air drying, heated-air drying and reduced-pressuredrying can be used.

There is no special limitation on the electrode structure when anodeelectrode active material is made into an electrode by theabove-mentioned method. The density of the active material on thecurrent collector is preferably 1 g·cm⁻³ or higher, more preferably 1.2g·cm⁻³ or higher, still more preferably 1.3 g·cm⁻³ or higher, andusually 2 g·cm⁻³ or lower, preferably 1.9 g·cm⁻³ or lower, morepreferably 1.8 g·cm⁻³ or lower, still more preferably 1.7 g·cm⁻³ orlower. When the density exceeds the above-mentioned upper limit, activematerial particles are destroyed and an increase in initial irreversiblecapacity and deterioration in charge-discharge characteristic under highcurrent densities, caused by decrease in immersibility of thenon-aqueous liquid electrolyte near the interface of the currentcollector/active material, may result. When the density is below theabove range, conductivity in the active material may be poor, batteryresistance may increase and capacity per unit volume may be low.

[II-4. Cathode Electrode]

The cathode electrode of the first non-aqueous liquid electrolytesecondary battery of the present invention contains cathode electrodeactive material, similarly to a usual non-aqueous liquid electrolytesecondary battery.

Examples of cathode electrode active material include inorganiccompounds such as transition metal oxides, composite oxides oftransition metal and lithium (lithium transition metal composite oxide),transition metal sulfides and metal oxides, and metal lithium, lithiumalloys and their composites. Concrete examples are: transition metaloxides such as MnO, V₂O₅, V₆O₁₃ and TiO₂; lithium transition metalcomposite oxides such as LiCoO₂ or lithium cobalt composite oxide whosebasic composition is LiCoO₂, LiNiO₂ or lithium nickel composite oxidewhose basic composition is LiNiO₂, LiMn₂O₄ or LiMnO₂ or lithiummanganese composite oxide whose basic composition is LiMn₂O₄ or LiMnO₂,lithium nickel manganese cobalt composite oxide and lithium nickelcobalt aluminum composite oxide; transition metal sulfides such as TiSand FeS and metal oxides such as SnO₂ and SiO₂. Of these compounds,preferable are lithium transition metal composite oxides, moreconcretely LiCoO₂ or lithium cobalt composite oxide whose basiccomposition is LiCoO₂, LiNiO₂ or lithium nickel composite oxide whosebasic composition is LiNiO₂, LiMn₂O₄ or LiMnO₂ or lithium manganesecomposite oxide whose basic composition is LiMn₂O₄ or LiMnO₂, lithiumnickel manganese cobalt composite oxide and lithium nickel cobaltaluminum composite oxide, because they can provide both high capacityand excellent cycle characteristics. Lithium transition metal compositeoxides are preferable also because their chemical stability can beimproved by replacing a part of cobalt, nickel or manganese in thelithium transition metal composite oxide with other metals such as Al,Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga or Zr, because. Thesecathode electrode active materials can be used either singly or as amixture of more than one material in any combination and in any ratio.

The cathode electrode of the first non-aqueous liquid electrolytesecondary battery of the present invention can be produced according toa known method. Concretely, for example, the cathode electrode can beproduced using the above-mentioned cathode electrode active materialcombined with binder, electroconductor or the like, directly byroll-molding into a sheet electrode, by compression-molding into apellet electrode, by means of forming a cathode electrode activematerial layer applying the active material on a current collector for acathode electrode (hereinafter, referred to as “cathode electrodecurrent collector” as appropriate) (coating method), or by means offorming a thin layer (cathode electrode active material layer)containing the above cathode electrode active material on a currentcollector by vapor deposition, spattering, plating or the like. Usually,it is produced by the coating method.

When by the coating method, the above cathode electrode active materialis mixed with, for example, binder, thickener, electroconductor, solventor the like to be made into the form of slurry. Then the slurry isapplied to the cathode electrode current collector, dried and pressed toincrease its density, thereby the cathode electrode active materiallayer being formed on the cathode electrode current collector.

As materials of cathode electrode current collector can be citedaluminum, titanium, tantalum and alloy containing one or more of thesemetals. Of these, aluminum and its alloy are preferable.

The thickness of the cathode electrode current collector is usually 1 μmor greater, preferably 5 μm or greater, and usually 100 μm or less,preferably 50 μm or less. When the cathode electrode current collectoris too thick, the capacity of the entire battery may become too low. Onthe other hand, when it is too thin, its handling is sometimesdifficult.

In order to increase the bindability of the cathode electrode currentcollector to the cathode electrode active material layer formed thereon,it is preferable that the surface of the cathode electrode currentcollector is subjected to roughening procedure in advance. Examples ofsurface roughening methods include: blasting procedure; rolling with arough-surfaced roll; mechanical polishing in which the collector surfaceis polished with such means as an abrasive cloth or abrasive paper ontowhich abradant particles are adhered, a whetstone, an emery buff and awire brush equipped with steel wire; electropolishing; and chemicalpolishing.

In order to decrease the weight of the cathode electrode currentcollector and increase energy density of the battery per unit weight, itis also possible to use a perforated-type cathode electrode currentcollectors such as an expanded metal or a punching metal. This type ofcathode electrode current collector is freely adjustable in its weightby means of adjusting its ratio of perforation. Besides, when thecathode electrode active material layer is formed on both sides of thisperforated-type of cathode electrode current collector, the cathodeelectrode active material layer is riveted at these perforations andbecomes resistant to exfoliation of the cathode electrode activematerial layer. However, if the ratio of perforation is too high, bondstrength may rather decrease because the contact area between thecathode electrode active material layer and the cathode electrodecurrent collector becomes too small.

Usually, electroconductor is included in the cathode electrode activematerial layer in order to increase conductivity. There is no speciallimitation on the kind of electroconductor used. Concrete examples aremetallic materials, such as copper and nickel, and carbonaceousmaterial, e.g. graphite such as natural graphite and artificialgraphite, carbon black such as acetylene black and amorphous carbon likeneedle coke. These materials can be used either singly or as a mixtureof more than one kind in any combination and in any ratio.

The content of electroconductor in the cathode electrode active materiallayer is usually 0.01 weight 95 or higher, preferably 0.1 weight % orhigher, more preferably 1 weight % or higher, and usually 50 weight % orlower, preferably 30 weight % lower, more preferably 15 weight % orlower. When the content is too low, conductivity may be inadequate. Whenit is too high, capacity of the battery may decrease.

As binder to be used for the preparation of the cathode electrode activematerial layer, any such material can be used in the case of coatinginsofar as it is stable in a liquid medium used at the time of electrodepreparation. Concrete examples are: resin polymers such as polyethylene,polypropylene, polyethylene terephthalate, polymethyl metacrylate,aromatic polyamide, cellulose and nitrocellulose; rubber-type polymerssuch as SBR (styrene butadiene rubber), NBR (acrylonitrile butadienerubber), fluorinated rubber, isoprene rubber, butadiene rubber andethylene propylene rubber; thermoplastic elastomer-type polymers such asstyrene-butadiene-styrene block copolymer and its hydrogenated products,EPDM (ethylene-propylene-diene terpolymer), styrene ethylene butadieneethylene copolymer, styrene isoprene styrene block copolymer and itshydrogenated product; soft resin polymers such assyndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene vinylacetate copolymer and propylene α-olefin copolymer; fluorinated polymerssuch as polyfluorinated vinylidene, polytetrafluoroethylene, fluorinatedpolyfluorovinylidene and polytetrafluoroethylene ethylene copolymer; andhigh molecular composite materials having ionic conductivity for alkalimetal ion (especially lithium ion). These materials can be used eithersingly or as a mixture of more than one material in any combination andin any ratio.

The content of the binder in the cathode electrode active material layeris usually 0.1 weight % or higher, preferably 1 weight % or higher, morepreferably 5 weight % or higher, and usually 80 weight % or lower,preferably 60 weight % or lower, more preferably 40 weight % or lower,most preferably 10 weight % lower. When the content of the binder is toolow, the cathode electrode active material can not be adequatelyretained and mechanical strength of the cathode electrode may decrease,leading to deterioration of battery characteristics such as cyclecharacteristics. When the content is too high, battery capacity andconductivity may deteriorate.

As liquid medium for making slurry, any solvent can be used insofar asit can dissolve or disperse cathode electrode active material,electroconductor, binder and, as needed, thickener. Either aqueoussolvent or organic solvent can be used.

Examples of aqueous solvent include water, and mixture of water andalcohol. Examples of organic solvent include: aliphatic hydrocarbonssuch as hexane; aromatic hydrocarbons such as benzene, toluene, xyleneand methylnaphthalene; heteroaromatic compounds such as quinoline andpyridine; ketones such as acetone, methylethyl ketone and cyclohexanone;esters such as methyl acetate and methyl acrylate; amines such asdiethylene triamine and N,N-dimethylaminopropylamine; ethers such asdiethyl ether, propylene oxide and tetrahydrofuran (THF); amides such asN-methylpyrrolidone (NMP), dimethylformamide and dimethylacetamide; andnon-protonic polar solvents such as hexamethylphosphoramide anddimethylsulfoxide.

Especially when an aqueous solvent is used, it is preferable to preparethe slurry using a thickener and latex such as styrene butadiene rubber(SBR). A thickener is usually used to adjust the viscosity of slurry.There is no limitation on the kind of thickener. As concrete examplescan be cited carboxymethyl cellulose, methyl cellulose, hydroxymethylcellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch,phosphorylated starch, casein, and salts of these compounds. Thesecompounds can be used either singly or as a mixture of more than onecompound in any combination and in any ratio. When a thickener is used,the proportion of the thickener in the active material is usually 0.1weight % or higher, preferably 0.5 weight % or higher, more preferably0.6 weight % or higher, and usually 5 weight % or lower, preferably 3weight % or lower, more preferably 2 weight % or lower. When theproportion is below the above range, coatability may be extremely low.When the proportion exceeds the above range, the ratio of the activematerial in the cathode electrode active material layer decreases andthere is a possibility that battery capacity becomes low and resistancein the cathode electrode active materials become large.

No particular limitation is imposed on the viscosity of the slurry,insofar as the slurry can be applied on the current collector. Theamount of the solvent used at the time of slurry preparation can beadjusted appropriately to give a suitable viscosity for application.

Slurry obtained is applied on the above cathode electrode collector, andafter drying and pressing anode electrode active material layer isformed. No particular limitation is imposed on the method of applicationand known methods can be used. No particular limitation is imposed onthe method of drying either, and per se known methods such as airdrying, heated-air drying and reduced-pressure drying can be used.

It is preferable that the cathode electrode active material layerobtained through processes such as coating and drying is subjected toconsolidation process by such means as hand pressing or roller pressingin order to increase packing density of the cathode electrode activematerial.

The density of the cathode electrode active material is preferably 1.5g·cm⁻³ or higher, more preferably 2 g·cm⁻³ or higher, still morepreferably 2.2 g·cm⁻³ or higher, and preferably 3.5 g·cm⁻³ or lower,more preferably 3 g·cm⁻³ or lower, still more preferably 2.8 g·cm⁻³ orlower. When the density exceeds the above-mentioned upper limit, adecrease in immersibility of the non-aqueous liquid electrolyte near theinterface of the current collector/active material may occur anddeterioration in charge-discharge characteristic under high currentdensities may result. When the density is below the above range,conductivity in the active material may be poor and battery resistancemay increase.

[III-5. Separator]

Usually, a separator is installed between the cathode electrode and theanode electrode to prevent shortings. In the case, the first non-aqueousliquid electrolyte of the present invention is usually used in such away that the separator is impregnated with this liquid electrolyte.

There is no special limitation on the material or shape of the separatorinsofar as the advantage of the present invention is not significantlyimpaired. Any known ones can be used. It is particularly preferable touse porous sheet or nonwoven fabric, with good water-retainingcharacteristics, which is made of material stable in the non-aqueousliquid electrolyte of the present invention.

As materials of the separator can be used: polyolefin such aspolyethylene and polypropylene, polytetrafluoroethylene, polyethersulfone and glass filter. Of these materials, preferably are glassfilter and polyolefin. Particularly preferable is polyolefin. Thesematerials can be used either singly or as a mixture of more than onekind in any combination and in any ratio.

No particular limitation is imposed on the thickness of the separator.It is usually 1 μm or greater, preferably 5 μm or greater, morepreferably 10 μm or greater, and usually 50 μm or less, preferably 40 μmor less, more preferably 30 μm or less. When the separator is too thin,insulation property and mechanical strength may deteriorate. When it istoo thick, battery characteristics such as rate characteristics maydeteriorate and also energy density of the entire non-aqueous liquidelectrolyte secondary battery may decline.

When porous material such as porous sheet or nonwoven fabric is used asseparator, there is no special limitation on the porosity of theseparator. It is usually 20% or larger, preferably 35% or larger, morepreferably 45% or larger, and usually 90% or smaller, preferably 85% orsmaller, more preferably 75% or smaller. When the porosity is too small,membrane resistance may become large and rate characteristics maydeteriorate. When it is too large, mechanical strength of the separatormay decrease, leading to poor insulation property.

No particular limitation is imposed on the average pore diameter of theseparator. Usually, it is 0.5 μm or smaller, preferably 0.2 μm orsmaller, and usually 0.05 μm or larger. When the average pore diameteris too large, shortings are liable to occur. When it is too small,membrane resistance may become large and rate characteristics maydeteriorate.

[II-6. Outer Package]

The first non-aqueous liquid electrolyte secondary battery of thepresent invention is usually constituted by storing the abovenon-aqueous liquid electrolyte, anode electrode, cathode electrode andseparator or the like in an outer package. There is no speciallimitation on this outer package and any known one can be used insofaras the advantageous effect of the present invention is not significantlyimpaired.

Concretely, there is no special limitation on the material of the outerpackage. Usually, nickel-plated iron, stainless steel, aluminum and itsalloys, nickel and titanium are used.

There is no limitation on the shape of the outer package, either. Theshape may be cylindrical, prismatic, laminated, coin-like or large size.

[III. Others]

[III-1. Second Non-Aqueous Liquid Electrolyte and Non-Aqueous LiquidElectrolyte Secondary Battery]

The above-mentioned component (i) (specific compound (I) and thesaturated cyclic carbonate) may improve charge-discharge cyclecharacteristics of the non-aqueous liquid electrolyte secondary batteryeven when specific carbonate is not combined in the non-aqueous liquidelectrolyte. In the following, explanation will be given on thenon-aqueous liquid electrolyte which contains component (i) (specificcompound (I) and the saturated cyclic carbonate) and does not requirethe specific carbonate (non-aqueous liquid electrolyte related to thesecond subject of the present invention. Hereafter abbreviated as“second non-aqueous liquid electrolyte” as appropriate) and thenon-aqueous liquid electrolyte secondary battery based on it(abbreviated as “second non-aqueous liquid electrolyte secondary batteryof the present invention” as appropriate).

The second non-aqueous liquid electrolyte of the present invention is anon-aqueous liquid electrolyte to be used for a non-aqueous liquidelectrolyte secondary battery comprising a anode electrode and a cathodeelectrode, capable of intercalating and deintercalating lithium ions,and a non-aqueous liquid electrolyte, the anode electrode containing aanode electrode active material having at least one kind of atomselected from the group consisting of Si atom, Sn atom and Pb atom(specific metal element).

The second non-aqueous liquid electrolyte is characterized in that itcontains the above-mentioned component (i), namely the above-mentionedspecific compound (I) and saturated cyclic carbonate. The details of thespecific compound (I) and saturated cyclic carbonate are similar to whathas been described in <I-1-1. Component (i)>. The ratio of specificcompound (I) and the saturated cyclic carbonate in the secondnon-aqueous liquid electrolyte is also similar to the ratio of specificcompound (I) and the saturated cyclic carbonate in the non-aqueousliquid electrolyte (I) described in <I-1-1. Component (i)>.

The details (requirement, kind, ratio etc.) of components other thanspecific compound (I) and the saturated cyclic carbonate (non-aqueoussolvent, electrolyte, additive etc.) of the second non-aqueous liquidelectrolyte are similar to what has been described in each item ([1-3.Non-aqueous solvent], [I-4. Electrolyte], [I-5. Additive]) for theabove-mentioned [I. First non-aqueous liquid electrolyte].

The use of the second non-aqueous liquid electrolyte may improvecharge-discharge cycle characteristics of the non-aqueous liquidelectrolyte secondary battery based on the anode electrode activematerial containing the above-mentioned specific metal element, eventhough it does not contain the specific carbonate, as described above.The detailed reason is not clear but inferred as follows.

Namely, chemical reactivity of specific compound (I) of the secondnon-aqueous liquid electrolyte towards anode electrode active materialcontaining the above specific metal element is held low by the presenceof alkyl group or fluoroalkyl group with 3 or more carbon atoms. Sidereactions are thus suppressed and cycle deterioration is evaded. Similareffect is obtained when the total number of carbon atoms of alkyl orfluoroalkyl groups of specific compound (I) is 5 or more. And thesolubility of the electrolytes becomes higher by the presence ofsaturated cyclic carbonate combined with specific compound (I), leadingto improvement in charge-discharge cycle characteristics.

The details of the non-aqueous liquid electrolyte secondary batterybased on the second non-aqueous liquid electrolyte (second non-aqueousliquid electrolyte secondary battery), except those for the non-aqueousliquid electrolyte, are similar to what has been described in each item([II-1. Constitution of battery], [II-3. Anode electrode], [II-4.Cathode electrode], [II-5. Separator], [II-6. Outer package]) for theabove-mentioned [II. First non-aqueous liquid electrolyte secondarybattery].

The advantageous effect, however, is more pronounced when the specificcarbonate is present in the non-aqueous liquid electrolyte in additionto specific compound (I) and saturated cyclic carbonate (namely, theabove-mentioned first non-aqueous liquid electrolyte (I)) in comparisonwith the non-aqueous liquid electrolyte without specific carbonate(namely, second non-aqueous liquid electrolyte). As describedpreviously, it is inferred that, when the specific carbonate is combinedwith specific compound (I) and saturated cyclic carbonate, a protectivelayer is formed on the surface of the anode electrode active materialand side reaction is suppressed also, leading to improvement in propertyof the protective layer.

[III-2. Third Non-Aqueous Liquid Electrolyte and Non-Aqueous LiquidElectrolyte Secondary Battery]

The above-mentioned specific compound (II) may improve charge-dischargecycle characteristics of the non-aqueous liquid electrolyte secondarybattery when it is included in the non-aqueous liquid electrolyte singlyand the specific carbonate is not combined. In the following,explanation will be given on the non-aqueous liquid electrolyte whichcontains specific compound (II) and does not require the specificcarbonate (non-aqueous liquid electrolyte related to the third subjectof the present invention. Hereafter abbreviated as “third non-aqueousliquid electrolyte” as appropriate) and the non-aqueous liquidelectrolyte secondary battery based on it (abbreviated as “thirdnon-aqueous liquid electrolyte secondary battery of the presentinvention” as appropriate).

The third non-aqueous liquid electrolyte of the present invention is anon-aqueous liquid electrolyte to be used for a non-aqueous liquidelectrolyte secondary battery comprising a anode electrode and a cathodeelectrode, capable of intercalating and deintercalating lithium ions,and a non-aqueous liquid electrolyte, the anode electrode containing aanode electrode active material having at least one kind of atomselected from the group consisting of Si atom, Sn atom and Pb atom(specific metal element).

The third non-aqueous liquid electrolyte is characterized in that itcontains the above-mentioned specific compound (II). The details of thespecific compound (II) are similar to what has been described in <I-1-2.Component (ii)>. The ratio of specific compound (II) in the thirdnon-aqueous liquid electrolyte is also similar to the ratio of specificcompound (II) in the non-aqueous liquid electrolyte (II) described in<I-1-2. Component (ii)>.

The details (requirement, kind, ratio etc.) of components other thanspecific compound (II) (non-aqueous solvent, electrolyte, additive etc.)of the third non-aqueous liquid electrolyte are similar to what has beendescribed in each item ([I-3. Non-aqueous solvent], [I-4. Electrolyte],[I-5. Additive]) for the above-mentioned [I. First non-aqueous liquidelectrolyte].

The use of the third non-aqueous liquid electrolyte makes it possible toimprove charge-discharge cycle characteristics of the non-aqueous liquidelectrolyte secondary battery based on the anode electrode activematerial containing the above-mentioned specific metal element, eventhough it does not contain the specific carbonate, as described above.The detailed reason is not clear but inferred that the specific compound(II) forms an efficient protective layer on the surface of the anodeelectrode active material, thereby suppressing side reactions andinhibiting cycle deterioration.

The details of the non-aqueous liquid electrolyte secondary batterybased on the third non-aqueous liquid electrolyte (third non-aqueousliquid electrolyte secondary battery), except those for the non-aqueousliquid electrolyte, are similar to what has been described in each item([II-1. Constitution of battery], [II-3. Anode electrode], [II-4.Cathode electrode], [II-5. Separator], [II-6. Outer package]) for theabove-mentioned [II. First non-aqueous liquid electrolyte secondarybattery].

The advantageous effect, however, is more pronounced when the specificcarbonate is present in the non-aqueous liquid electrolyte in additionto specific compound (II) (namely, the above-mentioned first non-aqueousliquid electrolyte (II)) in comparison with the non-aqueous liquidelectrolyte without specific carbonate (namely, third non-aqueous liquidelectrolyte). As described previously, it is inferred that, when thespecific carbonate is combined with specific compound (II), a protectivelayer is formed on the surface of the anode electrode active materialand side reaction is suppressed also, leading to improvement in propertyof the protective layer.

[III-3. Fourth Non-Aqueous Liquid Electrolyte and Non-Aqueous LiquidElectrolyte Secondary Battery]

The non-aqueous liquid electrolyte containing both above-mentionedspecific compound (III) and the specific carbonate may improvecharge-discharge cycle characteristics not only in non-aqueous liquidelectrolyte secondary battery based on anode electrode active materialhaving at least one kind of atom selected from the group consisting ofSi atom, Sn atom and Pb atom (specific metal element), but also innon-aqueous liquid electrolyte secondary battery based on other anodeelectrode active material (non-aqueous liquid electrolyte based ongraphite material etc.). In the following, explanation will be given onthe non-aqueous liquid electrolyte which has no limitation on the kindof anode electrode active material (non-aqueous liquid electrolyterelated to the fourth subject of the present invention. Hereafterabbreviated as “fourth non-aqueous liquid electrolyte” as appropriate),and the non-aqueous liquid electrolyte secondary battery based on thatnon-aqueous liquid electrolyte (hereafter referred to as “fourthnon-aqueous liquid electrolyte secondary battery of the presentinvention” as appropriate).

The fourth non-aqueous liquid electrolyte of the present invention is anon-aqueous liquid electrolyte to be used for a non-aqueous liquidelectrolyte secondary battery comprising a anode electrode and a cathodeelectrode, capable of intercalating and deintercalating lithium ions,and a non-aqueous liquid electrolyte. It is characterized in that itcontains the above-mentioned specific compound (III) and specificcarbonate.

The details of the specific compound (III) and specific carbonate aresimilar to what has been described in <I-1-3. Component (iii)> and [I-2.Specific carbonate]. The proportion of the specific compound (III) andspecific carbonate in the fourth non-aqueous liquid electrolyte is alsosimilar to the proportion of the specific compound (III) and specificcarbonate in the non-aqueous liquid electrolyte (III) described in<I-1-3. Component (iii)> and [I-2. Specific carbonate].

The details (requirement, kind, ratio etc.) of components other thanspecific compound (III) and specific carbonate (non-aqueous solvent,electrolyte, additive etc.) of the fourth non-aqueous liquid electrolyteare similar to what has been described in each item ([I-3. Non-aqueoussolvent], [I-4. Electrolyte], [I-5. Additive]) for the above-mentioned[I. First non-aqueous liquid electrolyte].

The non-aqueous liquid electrolyte secondary battery based on the fourthnon-aqueous liquid electrolyte (fourth non-aqueous liquid electrolytesecondary battery) differs from the above-mentioned first non-aqueousliquid electrolyte secondary battery in that there is no limitation onthe kind of anode electrode active material that can be used. In thefollowing, explanation will be given on the anode electrode activematerial that can be used for the fourth non-aqueous liquid electrolytesecondary battery.

No particular limitation is imposed on the anode electrode activematerial. Examples include carbonaceous materials, metal materials,metal lithium and lithium alloys, which are capable of intercalating anddeintercalating lithium. Further, the anode electrode active materialscan be used either singly or as a mixture of more than one kind in anycombination and in any ratio.

Of these, preferable are carbonaceous materials, alloys consisting oflithium and more than one kind of metal capable of intercalating anddeintercalating lithium, and composite compound materials such asborides, oxides, nitrides, sulfides and phosphides of these metals.

Any carbonaceous material can be used as anode electrode activematerial. Preferable are graphite, and graphite whose surface is coveredwith carbon which is more amorphous than graphite.

For the above-mentioned graphite, it is preferable that the d value(interlayer distance) of the lattice plane (002 plane), obtained by Xray diffraction according to the Gakushin method, is usually 0.335 nm orlarger, and usually 0.338 nm or smaller, preferably 0.337 nm or smaller.

Furthermore, it is preferable for the graphite that its crystallite size(Lc), obtained by X ray diffraction according to the Gakushin method, isusually 30 nm or larger, more preferably 50 nm or larger, still morepreferably 100 nm or larger.

The ash content of the graphite is usually 1 weight % or less,preferably 0.5 weight % or less, more preferably 0.1 weight % or less.

When the surface of the graphite is covered with amorphous carbon, it ispreferable to use as nucleus material graphite whose d value of thelattice plane (002 plane), obtained by X ray diffraction, is usually0.335 nm to 0.338 nm, and to use as covering material carbonaceousmaterial whose d value of the lattice plane (002 plane), obtained by Xray diffraction, is larger than that of the nucleus material.Furthermore, it is preferable that the weight ratio of the nucleusmaterial and the covering material whose d value of the lattice plane(002 plane), obtained by X ray diffraction, is larger than that of thenucleus material is usually in the range of 9/1 to 80/20. The use ofthis material makes possible the production of anode electrode with highcapacity and low reactivity towards the non-aqueous liquid electrolyte.

There is no special limitation on the particle diameter of thecarbonaceous material, insofar as the advantage of the present inventionis not significantly impaired. The median diameter, measured by thelaser diffraction-scattering method is usually 1 μm or larger,preferably 3 μm or larger, more preferably 5 μm or larger, still morepreferably 7 μm or larger. On the other hand, its upper limit is usually100 μm or smaller, preferably 50 μm or smaller, more preferably 40 μm orsmaller, still more preferably 30 μm or smaller. When the diameter isbelow the lower limit of the above range, the specific surface area maybe too large. When it exceeds the upper limit thereof, the specificsurface area may be too small.

There is no special limitation on the specific surface area of thecarbonaceous material, either, as measured by the BET method, insofar asthe advantage of the present invention is not significantly impaired. Itis usually 0.3 m²/g or larger, preferably 0.5 m²/g or larger, morepreferably 0.7 m²/g or larger, still more preferably 0.8 m²/g or larger.On the other hand, its upper limit is usually 25.0 m²/g or smaller,preferably 20.0 m²/g or smaller, more preferably 15.0 m²/g or smaller,still more preferably 10.0 m²/g or smaller. When the value is below thelower limit of the above range, a sufficiently large area necessary forthe insertion and release of lithium ions can not be secured.

When the upper limit is exceeded, reactivity of the liquid electrolytemay be too high.

It is preferable that when the carbonaceous material is examined inaccordance with Raman spectroscopy employing argon ion laser light, theR value (═I_(B)/I_(A)), represented by the ratio between the peakstrength I_(A) of peak spectrum P_(A), existing in the range of 1570cm⁻¹ to 1620 cm⁻¹, and the peak strength I_(B) of peak spectrum P_(B),existing in the range of 1300 cm⁻¹ to 1400 cm⁻¹, of the carbonaceousmaterial is in the range of usually 0.01 or larger and 0.7 or smaller,from the standpoint of realizing effective battery characteristics.

In this connection, it is preferable for good battery characteristicsthat, when carbonaceous material is subjected to Raman spectrum analysisusing argon ion laser light, the half-height width of the peak appearingin the range of 1570 cm⁻¹ to 1620 cm⁻¹ is usually 26 cm⁻¹ or less, morepreferably 25 cm⁻¹ or less

When alloy consisting of lithium and one or more kind of metal capableof intercalating and deintercalating lithium, or composite compoundmaterial such as boride, oxide, nitride, sulfide or phosphide of thesemetals is used as anode electrode active material, it is possible touse, as the alloy or composite compound material, alloy containing morethan one metal element or, further, its composite compound material. Forexample, it is also possible to use materials in which metal alloys orboride, oxide, nitride, sulfide or phosphide of these alloys arechemically bonded in a complex manner.

Of the anode electrode active materials consisting of the above alloy orcomposite compound material, preferable are those containing Si, Sn orPb, and particularly preferable are those containing Si or Sn, from thestandpoint of large capacity per unit weight of the anode electrode whenmade into a non-aqueous liquid electrolyte secondary battery.

The proportion of the anode electrode active material and the details ofthe anode electrode of the fourth non-aqueous liquid electrolytesecondary battery, except those of the anode electrode active material,are similar to what has been described in [II-3. Anode electrode] of theabove-mentioned [II. First non-aqueous liquid electrolyte secondarybattery].

The details of the fourth non-aqueous liquid electrolyte secondarybattery, except those for the non-aqueous liquid electrolyte and theanode electrode, are similar to what has been described in each item([II-1. Constitution of battery], [II-4. Cathode electrode], [II-5.Separator], [II-6. Outer packaging]) of the above-mentioned [II. Firstnon-aqueous liquid electrolyte secondary battery].

As described above, the fourth non-aqueous liquid electrolyte can bringabout improvement in charge-discharge cycle characteristics of not onlythe non-aqueous liquid electrolyte secondary battery based on anodeelectrode active material containing specific metal element, but alsothe battery based on various anode electrode active material. Althoughdetailed reason is not clear, it is inferred that, similarly to what hasbeen described for the first non-aqueous liquid electrolyte (non-aqueousliquid electrolyte (III)), an effective protective layer is formed onthe surface of the anode electrode active material by the reactivity ofboth specific compound (III) and specific carbonate contained in thenon-aqueous liquid electrolyte (III), and side reaction is therebysuppressed, leading to inhibition of cycle deterioration.

The advantageous effect, however, is more pronounced when the anodeelectrode active material containing the above specific metal element isused for the non-aqueous liquid electrolyte secondary battery (namely,first non-aqueous liquid electrolyte) than when other anode electrodeactive material is used for the non-aqueous liquid electrolyte secondarybattery (namely, fourth non-aqueous liquid electrolyte).

EXAMPLES

The present invention will be explained in further detail belowreferring to examples. It is to be understood that any modification ispossible to these examples insofar as it does not depart from the scopeof the invention.

Example•Comparative Example Group I Examples I-1 to 1-14 and ComparativeExamples I-1 to 1-4

Non-aqueous liquid electrolyte secondary batteries were assembled by thefollowing procedure and their performance were evaluated. The resultsare shown in Table I.

Preparation of Anode Electrode Preparation of Silicon Alloy AnodeElectrode: Examples I-1 to I-14, Comparative Examples I-1, I-2

As anode electrode active material were used 73.2 weight parts ofsilicon, a non-carbonaceous material, 8.1 weight parts of copper and12.2 weight parts of artificial graphite powder (product of Timcar Co.“KS-6”). To the mixture were added 54.2 weight parts ofN-methylpyrrolidone solution, containing 12 weight parts ofpolyvinylidene fluoride (hereafter abbreviated as “PVDF”), and 50 weightparts of N-methylpyrrolidone, and the mixture was made into slurry usinga disperser. The slurry obtained was coated uniformly onto a copper filmof 18 μm thickness, which is a anode electrode current collector. Thecoated film was first air-dried and finally reduced pressure-driedovernight at 85° C., and then pressed to give an electrode density ofabout 1.5 g·cm⁻³. A disk of 12.5 mm diameter was stamped out to preparethe anode electrode (silicon alloy anode electrode).

Preparation of Graphite Anode Electrode: Comparative Examples 1-3, I-4

As anode electrode was used 100 weight parts of artificial graphitepowder (product of Timcar Co. “KS-6”). To this were added 83.5 weightparts of N-methylpyrrolidone, containing 12 weight parts of PVDF, and 50weight parts of N-methylpyrrolidone, and the mixture was made intoslurry using a disperser. The slurry obtained was coated uniformly ontoa copper film of 18 μm thickness, which is a anode electrode currentcollector. The coated film was first air-dried and finally reducedpressure-dried overnight at 85° C., and then pressed to give anelectrode density of about 1.5 g·cm⁻³. A disk of 12.5 mm diameter waspunched out to prepare the anode electrode (graphite anode electrode).

[Preparation of Cathode Electrode]

As cathode electrode active material was used 85 weight parts of LiCoO₂(product of Nihon Kagaku Kogyo Co. “C5”). To this were added 6 weightparts of carbon black (product of Denki Kagaku Kogyo Co. “Denka Black”)and 9 weight parts of polyvinylidene fluoride KF-1000 (product of KurehaKagaku Co. “KF-1000”). After mixing, the mixture was dispersed intoslurry using N-methyl-2-pyrrolidone. The slurry obtained was coateduniformly onto a aluminum film of 20 μm thickness, which is the cathodeelectrode current collector, so that its amount represents 90 of thetheoretical capacity of the anode electrode. After drying at 100° C. for12 hours, a disk of 12.5 mm diameter was stamped out to prepare thecathode electrode.

[Preparation of Non-Aqueous Liquid Electrolyte]

[Specific carbonate], [other compound] and [specific component]described in each [Example] and [Comparative Example] of Table Iappearing later were mixed in a ratio specified in the Table. LiPF₆ wasdissolved as electrolyte salt at a concentration of 1 mol·dm⁻³ toprepare the non-aqueous liquid electrolyte (non-aqueous liquidelectrolyte of Examples I-1 to I-14 and Comparative Examples I-1 to1-4).

[Preparation of Coin-Type Cell]

By using the above cathode electrode and anode electrode, and thenon-aqueous liquid electrolyte prepared in each Example and ComparativeExample, the coin-type cell (non-aqueous liquid electrolyte secondarybattery of Examples I-1 to I-14 and Comparative Examples I-1 to I-4) wasprepared by the following procedure: at 25° C., the cathode electrodewas installed in a stainless steel can-body which also functions ascathode electrode current collector. Onto the cathode electrodeinstalled, the anode electrode was placed with a separator, made ofpolyethylene and impregnated with the liquid electrolyte, interposed inboth electrode. Then the can-body was sealed by caulking with a sealingpad, which also functions as anode electrode current collector, with agasket for insulation interposed between the can-body and the pad,thereby the coin-type cell being prepared. As anode electrode, theabove-mentioned silicon alloy anode electrode or graphite anodeelectrode was selected and used, according to the description of [anodeelectrode] column in each [Example] and [Comparative Example] of Table Iappearing later.

For the coin-type cell obtained by the above procedure (non-aqueousliquid electrolyte secondary battery of Examples I-1 to I-14 andComparative Examples I-1 to I-4), the discharge capacity and dischargecapacity retention were evaluated by the following procedure: eachcoin-type cell was first charged with constant current and constantvoltage at the charge termination voltage of 4.2V-3 mA and at the chargetermination current of 0.15 μA, and then discharged with constantcurrent at the discharge termination voltage of 3.0V-3 mA. Thischarge-discharge cycle was repeated 50 times. Discharge capacities atthe 1st, 10th and 50th cycle were measured at this point. Dischargecapacity retentions after the 10th cycle and 50th cycle were calculatedaccording to the following formula.

discharge capacity retention(%)=100*(discharge capacity at the 10th or50th cycle)/(discharge capacity at the 1st cycle)  [Mathematical Formula1]

Discharge capacity at the 1st, 10th and 50th cycle and dischargecapacity retention (%) at the 10th and 50th cycle obtained for thecoin-type cell of each example and comparative example are shown in thecolumn [battery evaluation] of Table I below. Values of dischargecapacity shown in Table I indicate capacity per unit weight of anodeelectrode active material (mAh·g⁻¹). “Wt %” indicates “weight %”.

TABLE I battery evaluation at the 10th cycle at the 50th cyclenon-aqueous liquid electrolyte discharge discharge discharge negative-combination of non- capacity capacity capacity electrode aqueoussolvents at the discharge retention discharge retention active (figuresin parentheses 1st cycle capacity rate capacity rate Examples materialmeans volume ratio)* specific carbonate* (mAh/g) (mAh/g) (%) (mAh/g) (%)Examples I-1 Si Alloy EC + EPC (30:70) FEC (5 wt %) 609 508 83.4 35758.7 I-2 EC + EPC (30:70) VC (5 wt %) 605 495 81.9 352 58.2 I-3 EC + EPC(30:70) DFEC (5 wt %) 608 505 83.1 357 58.7 I-4 EC + FEC + EPC(15:15:70) (contained as saturated 612 520 84.9 367 59.9 cycliccarbonate) I-5 FEC + EPC (30:70) (contained as saturated 608 515 84.7359 59.1 cyclic carbonate) I-6 FEC + EPC (30:70) VC (5 wt %) 603 52086.3 341 56.5 I-7 EC + DPC + DEC (30:50:20) VC (5 wt %) 602 494 82.1 34657.4 I-8 EC + EMFPC (30:70) (contained as specific 601 498 82.8 338 56.3compound (I)) I-9 EC + PTFEC (30:70) (contained as specific 600 499 83.1337 56.2 compound (I)) I-10 FEC + EMFPC (30:70) (contained as saturated604 511 84.6 361 59.7 cyclic carbonate and specific compound (I)) I-11FEC + PTFEC (30:70) (contained as saturated 606 516 85.1 357 58.9 cycliccarbonate and specific compound (I)) I-12 FEC + EMFPC (30:70) VC (5 wt%) 604 519 86.0 358 59.2 I-13 EC + EPC (30:70) — 602 499 82.9 333 55.3I-14 EC + DPC + DEC (30:50:20) — 598 492 82.2 328 54.9 Comparative I-1EC + DMC (30:70) — 599 287 47.8 91 15.1 Examples I-2 EC + EMC (30:70) —603 321 53.2 113 18.7 I-3 graphite EC + EMC (30:70) — 345 342 99.2 31190.1 I-4 EC + EPC (30:70) — 338 332 98.3 290 85.8  EC: ethylenecarbonate (saturated cyclic carbonate) FEC: fluoroethylene carbonate(saturated cyclic carbonate and specific carbonate; the number ofsubstituting F is 1) DFEC: 4,5-difluoroethylene carbonate (saturatedcyclic carbonate and specific carbonate; the number of substituting F is2) EPC: ethyl n-propyl carbonate (specific compound (I); n = 3, m = 2)DPC: dipropyl carbonate (specific compound (I); n = m = 3) PTFEC:n-propyl trifluoroethyl carbonate (specific compound (I) and specificcarbonate; n = 3, m = 2, the number of substituing F is 3) EMFPC: ethyl3-monofluoropropyl carbonate (specific compound (I) and specificcarbonate; n = 3, m = 2, the number of substituting F is 1) DEC: diethylcarbonate (other chain carbonate) DMC: dimethyl carbonate (other chaincarbonate) EMC: ethyl methyl carbonate (other chain carbonate)

The results shown in Table I above indicate the following.

In Comparative Examples I-1 and I-2, the non-aqueous liquid electrolytedoes not contain specific compound (I) (linear carbonate represented bythe above general formula (I)) and therefore discharge capacityretention after cycle test is low in either case.

In Comparative Examples I-3 and I-4, carbon material is used as anodeelectrode active material. The non-aqueous liquid electrolyte incomparative example I-3 does not contain specific compound (I) and thatin comparative example I-4 contains specific compound (I). However,comparison between Comparative Example I-3 and Comparative Example I-4indicates that the use of specific compound (I) does not contribute tothe improvement of discharge capacity retention after cycle test,because the anode electrode active material is carbon material.Therefore, when carbon material is used as anode electrode activematerial, enhancing effect for cycle characteristics can not be expectedfor specific compound (I).

On the other hand, in the non-aqueous liquid electrolyte secondarybattery of Examples I-1 to I-12, where silicon alloy or the like is usedas anode electrode active material and the non-aqueous liquidelectrolyte containing specific compound (I), the saturated cycliccarbonate and the specific carbonate, the discharge capacity retentionis improved remarkably in every case in comparison with comparativeexample I-1 and I-2, which indicates excellent cycle characteristics.

Furthermore, in Examples 1-13 and I-14, where the non-aqueous liquidelectrolyte contains specific compound (I) and the saturated cycliccarbonate but not the specific carbonate, discharge capacity retentionafter cycle test is greatly improved in comparison with ComparativeExamples I-1 and I-2, although the degree of improvement is slightlyless than that for the above Examples I-1 to I-12.

Example•Comparative Example Group II Examples II-1 to II-28 andComparative Examples II-1 to II-14

The non-aqueous liquid electrolyte secondary battery was assembled bythe following procedure and its performance was evaluated. The resultsare shown in Tables II-1 to II-6.

Preparation of Anode Electrode Preparation of Silicon Alloy AnodeElectrode: Examples II-1 to II-28, Comparative Examples II-1 to II-3,II-9, II-10>

The anode electrode (silicon alloy anode electrode) was prepared by thesame method as described in the section <Preparation of silicon alloyanode electrode> of the above-mentioned [Example•Comparative ExampleGroup I].

Preparation of Graphite Anode Electrode: Examples II-4 to II-8, II-11 toII-14

The anode electrode (graphite anode electrode) was prepared by the samemethod as described in the section <preparation of graphite anodeelectrode> of the above-mentioned [Example•Comparative Example Group I].

[Preparation of Cathode Electrode]

The cathode electrode was prepared by the same method as described inthe section <Preparation of cathode electrode> of the above-mentioned[(Example•Comparative Example Group I].

[Preparation of Non-Aqueous Liquid Electrolyte]

[Specific carbonate], [other compound] and [specific component]described in [Example] and [Comparative Example] of Table II-1 to II-6appearing later were mixed in a ratio specified in the Table. LiPF₆ wasdissolved as electrolyte salt at a concentration of 1 mol·dm⁻³ toprepare the non-aqueous liquid electrolyte (non-aqueous liquidelectrolyte of Examples II-1 to II-28 and Comparative Examples II-1 toII-14).

[Preparation of Coin-Type Cell]

By using the above cathode electrode and anode electrode, and thenon-aqueous liquid electrolyte prepared in each Example and ComparativeExample, the coin-type cell (non-aqueous liquid electrolyte secondarybattery of Examples II-1 to II-28 and Comparative Examples II-1 toII-14) was prepared by the same procedure as described in [Preparationof coin-type cell] of the above-mentioned [Example•Comparative ExampleGroup I].

[Evaluation of Coin-Type Cell (Discharge Capacity and Discharge CapacityRetention)]

For the coin-type cell obtained above (non-aqueous liquid electrolytesecondary battery of Examples II-1 to II-28 and Comparative ExamplesII-1 to II-14), discharge capacity at the 1st cycle and the 10th cyclewas measured by the same procedure as described above in [Evaluation ofcoin-type cell] of Example•Comparative Example Group I]. Dischargecapacity retention at the 10th cycle was calculated according to thefollowing formula.

discharge capacity retention(%)=100*(discharge capacity at the 10thcycle)/(discharge capacity at the 1st cycle)  [Mathematical Formula 2]

Discharge capacity at the 1st and 10th cycle and discharge capacityretention (%) at the 10th cycle obtained for the coin-type cell of eachexample and comparative example are shown in the column [batteryevaluation] of Tables II-1 to II-6 below. Values of discharge capacityshown in Tables II-1 to II-6 indicate capacity per unit weight of anodeelectrode active material (mAh·g⁻¹). Herein, “wt %” indicates “weight%”, and “vt %” indicates “volume %”.

TABLE II-1 battery evaluation non-aqueous liquid electrolyte dischargedischarge discharge specific capacity at the capacity at the capacitynegative carbonate other compound specific compound (II) 1st cycle 10thcycle retention rate electrode (concentration) (concentration)(concentration) (mAh · g−1) (mAh · g−1) (%) Example II-1 Si alloyfluoroethylene ethylene carbonate + bis(trimethylsilyl)sulfate 631 57190.5 carbonate (5 wt %) diethyl carbonate (2 wt %) (34 wt % + 59 wt %)Example II-2 Si alloy fluoroethylene ethylene carbonate +bis(trimethylsilyl)sulfate 627 560 89.3 carbonate (5 wt %) diethylcarbonate (1 wt %) (34.5 wt % + 59.5 wt %) Example II-3 Si alloyfluoroethylene diethyl carbonate bis(trimethylsilyl)sulfate 640 610 95.3carbonate (59 wt %) (2 wt %) Example II-4 Si alloy fluoroethyleneethylene carbonate + bis(trimethylsilyl)sulfate 638 595 93.3 carbonatediethyl carbonate (2 wt %) (20 wt %) (17.5 wt % + 60.5 wt %) ExampleII-5 Si alloy vinylene ethylene carbonate + bis(trimethylsilyl)sulfate622 535 86 carbonate (5 wt %) diethyl carbonate (2 wt %) (34 wt % + 59wt %) Example II-6 Si alloy 4,5- ethylene carbonate +bis(trimethylsilyl)sulfate 636 590 92.7 difluoroethylene diethylcarbonate (2 wt %) carbonate (5 wt %) (34 wt % + 59 wt %) Example II-7Si alloy fluoroethylene diethyl carbonate bis(trimethylsilyl)sulfate 643614 95.5 carbonate + (58 wt %) (2 wt %) vinylene carbonate Example II-8Si alloy fluoroethylene diethyl carbonate bis(trimethylsilyl)sulfate 642612 95.4 carbonate + (58 wt %) (2 wt %) vinylethylene carbonate (38 wt% + 2 wt %)

TABLE II-2 battery evaluation non-aqueous liquid electrolyte dischargedischarge discharge specific capacity at the capacity at the capacitynegative carbonate other compound specific compound (II) 1st cycle 10thcycle retention rate electrode (concentration) (concentration)(concentration) (mAh · g−1) (mAh · g−1) (%) Example II-9 Si alloyfluoroethylene ethylene carbonate + bis(trimethylsilyl)sulfate 629 56489.6 carbonate (5 wt %) diethyl carbonate (2 wt %) (34 wt % + 59 wt %)Example Si alloy 4,5- ethylene carbonate + bis(trimethylsilyl)sulfate631 573 90.8 II-10 difluoroethylene diethyl carbonate (2 wt %) carbonate(5 wt %) (34 wt % + 59 wt %) Example Si alloy fluoroethylene diethylcarbonate bis(trimethylsilyl)sulfate 634 589 92.9 II-11 carbonate (59 wt%) (2 wt %) Example Si alloy fluoroethylene diethyl carbonatebis(trimethylsilyl)sulfate 640 602 94 II-12 carbonate + (58 wt %) (2 wt%) vinylene carbonate (38 wt % + 2 wt %) Example Si alloy fluoroethyleneethylene carbonate + bis{tris(2,2,2- 636 578 90.9 II-13 carbonate (5 wt%) diethyl carbonate triethyl)}silylsulfate (2 wt %) (34 wt % + 59 wt %)Example Si alloy 4,5- ethylene carbonate + bis{tris(2,2,2- 639 589 92.2II-14 difluoroethylene diethyl carbonate triethyl)}silylsulfate (2 wt %)carbonate (5 wt %) (34 wt % + 59 wt %) Example Si alloy fluoroethylenediethyl carbonate bis{tris(2,2,2- 642 609 95 II-15 carbonate (59 wt %)triethyl)}silylsulfate (2 wt %) Example Si alloy fluoroethylene diethylcarbonate bis{tris(2,2,2- 645 616 95 II-16 carbonate + (58 wt %)triethyl)}silylsulfate (2 wt %) vinylethylene carbonate (38 wt % + 2 wt%)

TABLE II-3 battery evaluation non-aqueous liquid electrolyte dischargedischarge discharge specific capacity at the capacity at the capacitynegative carbonate other compound specific compound (II) 1st cycle 10thcycle retention rate electrode (concentration) (concentration)(concentration) (mAh · g−1) (mAh · g−1) (%) Example II-17 Si alloyfluoroethylene ethylene carbonate + bis(trimethylsilyl)sulfite 634 57490.5 carbonate (5 wt %) diethyl carbonate (2 wt %) (34 wt % + 59 wt %)Example II-18 Si alloy 4,5- ethylene carbonate +bis(trimethylsilyl)sulfite 636 588 92.4 difluoroethylene diethylcarbonate (2 wt %) carbonate (5 wt %) (34.5 wt % + 59.5 wt %) ExampleII-19 Si alloy fluoroethylene diethyl carbonatebis(trimethylsilyl)sulfite 640 603 94.2 carbonate (59 wt %) (2 wt %)Example II-20 Si alloy fluoroethylene diethyl carbonatebis(trimethylsilyl)sulfite 643 610 94.9 carbonate + (58 wt %) (2 wt %)vinylethylene carbonate (38 wt % + 2 wt %) Example II-21 Si alloy noneethylene carbonate + bis(trimethylsilyl)sulfite 618 510 82.5 diethylcarbonate (2 wt %) (36 wt % + 62 wt %)

TABLE II-4 battery evaluation non-aqueous liquid electrolyte dischargedischarge discharge specific capacity at the capacity at the capacitynegative carbonate other compound specific compound (II) 1st cycle 10thcycle retention rate electrode (concentration) (concentration)(concentration) (mAh · g−1) (mAh · g−1) (%) Example II-22 Si alloy noneethylene carbonate + bis(trimethylsilyl)sulfate 620 580 93.6 ethylmethylcarbonate (2 wt %) (30vt % + 70vt %) Example II-23 Si alloy noneethylene carbonate + bis(trimethylsilyl)sulfate 628 592 94.3 ethylmethylcarbonate (4 wt %) (30vt % + 70vt %) Example II-24 Si alloy noneethylene carbonate + bis(triethylsilyl)sulfate 615 571 92.8 ethylmethylcarbonate (2 wt %) (30vt % + 70vt %) Example II-25 Si alloy noneethylene carbonate + bis{tris (2,2,2- 608 571 93.9 ethylmethyl carbonatetrifluoroethyl)}silylsulfate (30vt % + 70vt %) (2 wt %) Example II-26 Sialloy none ethylene carbonate + bis(trimethylsilyl)sulfite 605 559 92.4ethylmethyl carbonate (2 wt %) (30vt % + 70vt %) Example II-27 Si alloyvinylene ethylene carbonate + bis(trimethylsilyl)sulfate 618 567 91.8carbonate (2 wt %) ethylmethyl carbonate (2 wt %) (30vt % + 70vt %)Example II-28 Si alloy vinylene ethylene carbonate +bis(trimethylsilyl)sulfite 603 553 91.7 carbonate (2 wt %) ethylmethylcarbonate (2 wt %) (30vt % + 70vt %)

TABLE II-5 battery evaluation non-aqueous liquid electrolyte dischargedischarge discharge specific capacity at the capacity at the capacitynegative carbonate other compound specific compound (II) 1st cycle 10thcycle retention rate electrode (concentration) (concentration)(concentration) (mAh · g−1) (mAh · g−1) (%) Comparative Si alloyfluoroethylene ethylene carbonate + none 615 494 80.3 Example II-1carbonate (5 wt %) diethyl carbonate (35 wt % + 60 wt %) Comparative Sialloy vinylene ethylene carbonate + none 611 455 74.5 Example II-2carbonate (5 wt %) diethyl carbonate (35 wt % + 60 wt %) Comparative Sialloy none ethylene carbonate + none 601 341 56.7 Example II-3 diethylcarbonate (37 wt % + 63 wt %) Comparative graphite none ethylenecarbonate + none 338 274 81.2 Example II-4 diethyl carbonate (37 wt % +63 wt %) Comparative graphite none ethylene carbonate +bis(trimethylsilyl)sulfite 332 269 81 Example II-5 diethyl carbonate (2wt %) (36 wt % + 62 wt %) Comparative graphite vinylene ethylenecarbonate + none 342 301 88 Example II-6 carbonate (5 wt %) diethylcarbonate (35 wt % + 60 wt %) Comparative graphite fluoroethyleneethylene carbonate + bis(trimethylsilyl)sulfite 335 255 71.8 ExampleII-7 carbonate (5 wt %) diethyl carbonate (2 wt %) (34 wt % + 59 wt %)Comparative graphite fluoroethylene diethyl carbonatebis(trimethylsilyl)sulfite 333 226 67.8 Example II-8 carbonate (59 wt %)(2 wt %)

TABLE II-6 battery evaluation non-aqueous liquid electrolyte dischargedischarge discharge specific capacity at the capacity at the capacitynegative carbonate other compound specific compound (II) 1st cycle 10thcycle retention rate electrode (concentration) (concentration)(concentration) (mAh · g−1) (mAh · g−1) (%) Comparative Si alloy noneethylene carbonate + none 603 537 89.1 Example II-9 ethylmethylcarbonate (30vt % + 70vt %) Comparative Si alloy vinylene ethylenecarbonate + none 612 550 89.9 Example II-10 carbonate (2 wt %)ethylmethyl carbonate (30vt % + 70vt %) Comparative graphite noneethylene carbonate + none 345 342 99.2 Example II-11 ethylmethylcarbonate (30vt % + 70vt %) Comparative graphite vinylene ethylenecarbonate + none 348 347 99.7 Example II-12 carbonate (2 wt %)ethylmethyl carbonate (30vt % + 70vt %) Comparative graphite noneethylene carbonate + bis(trimethylsilyl)sulfate 342 337 98.6 ExampleII-13 ethylmethyl carbonate (2 wt %) (30vt % + 70vt %) Comparativegraphite vinylene ethylene carbonate + bis(trimethylsilyl)sulfate 344340 98.9 Example II-14 carbonate (2 wt %) ethylmethyl carbonate (2 wt %)(30vt % + 70vt %)

The results shown in Tables II-1 to II-6 above indicate the following.

In Examples II-1 to II-20, II-27 and II-28, in which specific compound(II) and the specific carbonate are contained in the non-aqueous liquidelectrolyte, the discharge capacity retention after the cycle test isremarkably improved in comparison with Comparative Example II-3, inwhich neither specific compound (II) nor specific carbonate is containedin the non-aqueous liquid electrolyte.

Further, in Examples II-21 to II-26, in which the non-aqueous liquidelectrolyte contains only specific compound (II) and not specificcarbonate, the discharge capacity retention after the cycle test isremarkably improved also in comparison with comparative example II-3,although the degree of improvement is a little less than that observedin the above Examples II-1 to II-20, II-27 and II-28.

On the other hand, in Comparative Examples II-1 and II-2 where thenon-aqueous liquid electrolyte contains the specific carbonate but notspecific compound (II), the discharge capacity retention increases butthe degree of the increase is far less than that observed in ExamplesII-1 to II-20, II-27 and II-28.

In Comparative Examples II-4 to II-8 and II-11 to II-14, only carbonmaterial is used as anode electrode active material and in ComparativeExamples II-4, II-9 and II-11, the non-aqueous liquid electrolytecontains neither specific compound (II) nor specific carbonate. InComparative Example II-5, the non-aqueous liquid electrolyte containsonly specific compound (II) and not specific carbonate. Comparison indischarge capacity retention between Comparative Example II-4 andcomparative example II-5 indicates that inclusion of specific compound(II) does not affect discharge capacity retention.

The non-aqueous liquid electrolyte in Comparative Examples II-6, II-10and II-12 contains the specific carbonate but not specific compound(II). Comparison in discharge capacity retention between ComparativeExamples II-4, II-9, II-11 and Comparative Examples II-6, II-10, II-12indicates that inclusion of the specific carbonate improves dischargecapacity retention.

On the other hand, comparison between Comparative Examples II-7, II-8,II-14, whose non-aqueous liquid electrolyte contains both the specificcompound (II) and the specific carbonate, and Comparative Examples II-4,II-9, II-11, whose non-aqueous liquid electrolyte contains neitherspecific compound (II) or the specific carbonate, indicates thatdischarge capacity retention is worse in the former.

Discharge capacity in Examples II-1 to II-20, II-27, II-28, where anodeelectrode active material consists of silicon alloy, is higher than thatin Comparative Examples II-4 to II-8, II-11 to II-14, where anodeelectrode active material consists of carbon material alone. And, asmentioned above, when anode electrode active material consists of carbonmaterial, inclusion of either the specific carbonate or specificcompound (II) in the non-aqueous liquid electrolyte improves dischargecapacity retention. However, when specific compound (II) and thespecific carbonate are both included, discharge capacity retention islower than when none of these compound is included or when either one ofthese compounds is included.

On the other hand, when anode electrode active material consists ofsilicon alloy, a battery, based on the non-aqueous liquid electrolytecontaining only specific compound (II) and not the specific carbonate,has lower discharge capacity retention than a battery, based on thenon-aqueous liquid electrolyte containing neither of these compounds.However, a battery based on the non-aqueous liquid electrolytecontaining both specific compound (II) and specific carbonate showshigher discharge capacity retention.

Example•Comparative Example Group III Examples III-1 to III-19 andComparative Examples III-1 to III-7

The non-aqueous liquid electrolyte secondary battery was assembled bythe following procedure and its performance was evaluated. The resultsare shown in Table III-1 and III-2.

Preparation of Anode Electrode Preparation of Silicon Alloy AnodeElectrode: Examples III-1 to II-11, Comparative Examples II-1 to II-4

The anode electrode (silicon alloy anode electrode) was prepared by thesame method as described in the section <Preparation of silicon alloyanode electrode> of the above-mentioned [Example•Comparative ExampleGroup I].

Preparation of Graphite Anode Electrode: Examples III-12 to II-19,Comparative Examples II-5 to II-7

The anode electrode (graphite anode electrode) was prepared by the samemethod as described in the column <Preparation of graphite anodeelectrode> of the above-mentioned [Example•Comparative Example Group I].

[Preparation of Cathode Electrode]

The cathode electrode was prepared by the same method as described inthe column <Preparation of cathode electrode> of the above-mentioned[Example•Comparative Example Group I].

[Preparation of Non-Aqueous Liquid Electrolyte]

[Specific compound (III)] and [Specific carbonate] described in[Example] and [Comparative Example] of Tables III-1 and III-2 appearinglater were mixed in a ratio specified in the Table. LiPF₆ was dissolvedfurther as electrolyte salt at a concentration of 1 mol·dm⁻³ to preparethe non-aqueous liquid electrolyte (non-aqueous liquid electrolyte ofExamples III-1 to III-19 and Comparative Examples III-1 to III-7).

[Preparation of Coin-Type Cell]

By using the cathode electrode, anode electrode, and non-aqueous liquidelectrolyte prepared in each Example and Comparative Example, thecoin-type cell (non-aqueous liquid electrolyte secondary battery ofExamples III-1 to III-19 and Comparative Examples III-1 to III-7) wasprepared by the same procedure as described in [Preparation of coin-typecell] of the above-mentioned [Example•Comparative Example Group I].

[Evaluation of Coin-Type Cell (Discharge Capacity and Discharge CapacityRetention)]

For the non-aqueous liquid electrolyte secondary battery obtained inExamples III-1 to III-11 and Comparative Examples III-1 to III-4(coin-type cell), discharge capacity at the 1st cycle and the 100thcycle was measured by the same procedure as described above in[Evaluation of coin-type cell] of [Example•Comparative Example Group I].Discharge capacity retention at the 100th cycle was calculated accordingto the following formula.

discharge capacity retention(%)=100*(discharge capacity at the 100thcycle)/(discharge capacity at the 1st cycle)  [Mathematical Formula 3]

Further, for the non-aqueous liquid electrolyte secondary batteryobtained in Examples III-12 to III-19 and Comparative Examples III-5 toIII-7 (coin-type cell), discharge capacity at the 1st cycle and the 10thcycle was measured by the same procedure as described above in[Evaluation of coin-type cell] of [Example•Comparative Example Group I].Discharge capacity retention at the 10th cycle was calculated accordingto the following formula.

discharge capacity retention(%)=100*(discharge capacity at the 10thcycle)/(discharge capacity at the 1st cycle)  [Mathematical Formula 4]

Discharge capacity retention at the 100th cycle (%) obtained for thecoin-type cell of each example and comparative example is shown in thecolumn [battery evaluation] of Tables III-1 and III-2. Values ofdischarge capacity shown in Tables II-1 and II-2 indicate capacity perunit weight of anode electrode active material (mAh·g⁻¹). Herein, “wt %”indicates “weight %”.

TABLE 8 Table III-1 non-aqueous liquid electrolyte battery evaluationspecific compound (III) specific carbonate negative discharge capacitystructure amount name amount electrode at the 100th cycle Example III-1

2 wt % vinylene carbonate 2 wt % graphite 92% Example III-2

4 wt % vinylene carbonate 2 wt % graphite 93% Example III-3

2 wt % vinylene carbonate 4 wt % graphite 95% Example III-4

2 wt % vinylethylene carbonate 2 wt % graphite 90% Example III-5

2 wt % fluoroethylene carbonate 2 wt % graphite 90% Example III-6

2 wt % difluoroethylene carbonate 2 wt % graphite 90% Example III-7

2 wt % vinylene carbonate + vinylethylene carbonate 2 wt % + 2 wt %graphite 93% Example III-8

2 wt % vinylene carbonate + fluoroethylene carbonate 2 wt % + 2 wt %graphite 94% Example III-9

2 wt % vinylene carbonate + difluoroethylene carbonate 2 wt % + 2 wt %graphite 94% Example III-10

2 wt % vinylene carbonate 2 wt % graphite 93% Example III-11

2 wt % vinylene carbonate 2 wt % graphite 92% Compa- — — vinylenecarbonate 2 wt % graphite 88% rative Example III-1 Compa- — — vinylenecarbonate + 2 wt % + graphite 89% rative vinylethylene carbonate 2 wt %Example III-2 Compa- rative (Example III-3

— — graphite 79% Compa- rative Example III-4

— — graphite 75%

TABLE 9 Table III-2 battery non-aqueous liquid electrolyte dischargespecific compound (III) specific carbonate negative capacity at thestructure amount name amount electrode 10th cycle Example III-12

2 wt % vinylene carbonate 2 wt % Si alloy 93.5% Example III-13

2 wt % vinylene carbonate 2 wt % Si alloy 94.8% Example III-14

2 wt % fluoroethylene carbonate 2 wt % Si alloy 94.3% Example III-15

2 wt % difluoroethylene carbonate 2 wt % Si alloy 94.5% Example III-16

2 wt % fluoroethylene carbonate 30 wt % Si alloy 96.5% Example III-17

2 wt % difluoroethylene carbonate 30 wt % Si alloy 96.3% Example III-18

2 wt % vinylene carbonate + fluoroethylene carbonate 2 wt % Si alloy95.9% Example III-19

2 wt % vinylene carbonate + difluoroethylene carbonate 2 wt % Si alloy96.1% Compa- — — vinylene carbonate 2 wt % Si alloy 89.9% rative ExampleIII-5 Compa- — — vinylene carbonate + 2 wt % + Si alloy 91.2% rativevinylethylene carbonate 2 wt % Example III-6 Compa- rative Example III-7

2 wt % — — Si alloy 89.2%

The results shown in Tables III-1 and III-2 above indicate thefollowing.

When graphite is used in the anode electrode, it is evident thatExamples III-1 to III-11, in which specific compound (III) and thespecific carbonate are contained in the non-aqueous liquid electrolyte,give rise to a higher discharge capacity retention and better cyclecharacteristics than Comparative Examples III-1 to III-4.

Similar trend is also observed in the comparison between Examples III-12to III-19 and Comparative Examples III-5 to III-7, where silicon alloyis used in the anode electrode.

INDUSTRIAL APPLICABILITY

The non-aqueous liquid electrolyte secondary battery of the presentinvention is excellent in long-term charge-discharge cyclecharacteristics and, therefore, can be used as power source of notebookpersonal computers, pen-input personal computers, mobile computers,electronic book players, cellular phones, portable facsimiles, portablecopiers, portable printers, headphone stereos, video movies, liquidcrystal televisions, handy cleaners, portable CD players, mini discplayers, transceivers, electronic databooks, electronic calculators,memory cards, portable tape recorders, radios, backup power sources,motors, illuminators, toys, game machines, watches, stroboscopes,cameras, load leveling of power etc. and can also be used for electricbicycle, electric scooter, electric car etc.

Although the present invention was explained in detail referring tocertain embodiments, it is evident for those skilled in the art thatvarious changes or modifications can be made thereto without departingfrom the spirit and scope of the present invention.

The present application is based on Japanese Patent Application (PatentApplication No. 2004-326672) filed on Nov. 10, 2004, Japanese PatentApplication (Patent Application No. 2005-055337) filed on Mar. 1, 2005and Japanese patent Application (Patent Application No. 2005-183846)filed on Jun. 23, 2005, and their entireties are incorporated byreference.

1. A non-aqueous liquid electrolyte to be used for a non-aqueous liquidelectrolyte secondary battery comprising a anode electrode and a cathodeelectrode, capable of intercalating and deintercalating lithium ions,and the non-aqueous liquid electrolyte, the anode electrode containing aanode electrode active material having at least one kind of atomselected from the group consisting of Si atom, Sn atom and Pb atom,wherein said non-aqueous liquid electrolyte contains a carbonate havingat least either an unsaturated bond or a halogen atom, and also containsa compound represented by formula (III-1)A-N═C═O  (III-1) wherein in formula (III-1), A represents a chained orcyclic, saturated or unsaturated alkyl group that may be substituted. 2.The non-aqueous liquid electrolyte as defined in claim 1, wherein insaid non-aqueous liquid electrolyte, the concentration of said compoundrepresented by formula (III-1) is 0.01 weight % or higher, and 10 weight% or lower.
 3. The non-aqueous liquid electrolyte as defined in claim 1,wherein in said non-aqueous liquid electrolyte, the concentration ofsaid carbonate having at least either an unsaturated bond or a halogenatom is 0.01 weight % or higher, and 70 weight % or lower.
 4. Thenon-aqueous liquid electrolyte as defined in claim 1, wherein saidcarbonate having an unsaturated bond or a halogen atom is one or morecarbonate compounds selected from the group consisting of vinylenecarbonate, vinylethylene carbonate, fluoroethylene carbonate,difluoroethylene carbonate and derivatives of these carbonate compounds.5. The non-aqueous liquid electrolyte as defined in claim 1, furthercomprising ethylene carbonate and/or propylene carbonate.
 6. Thenon-aqueous liquid electrolyte as defined in claim 1, further comprisingat least one additional carbonate selected from the group consisting ofdimethyl carbonate, ethylmethyl carbonate, diethyl carbonate,methyl-n-propyl carbonate, ethyl-n-propyl carbonate and di-n-propylcarbonate.
 7. A non-aqueous liquid electrolyte secondary batterycomprising an anode electrode and a cathode electrode, capable ofintercalating and deintercalating lithium ions, and a non-aqueous liquidelectrolyte, the anode electrode containing an anode electrode activematerial having at least one kind of atom selected from the groupconsisting of Si atom, Sn atom and Pb atom, wherein said non-aqueousliquid electrolyte is the non-aqueous liquid electrolyte defined inclaim
 1. 8. A non-aqueous liquid electrolyte to be used for anon-aqueous liquid electrolyte secondary battery comprising a anodeelectrode and a cathode electrode, capable of intercalating anddeintercalating lithium ions, and the non-aqueous liquid electrolyte,wherein said non-aqueous liquid electrolyte contains, at least, acarbonate having at least either an unsaturated bond or a halogen atom,and a compound represented by formula (III-1) below.A-N═C═O  (III-1) wherein in the above formula (III-1), A represents anelement or group other than a hydrogen.
 9. The non-aqueous liquidelectrolyte as defined in claim 8, wherein in said non-aqueous liquidelectrolyte, the concentration of said compound represented by formula(III-1) is 0.01 weight % or higher, and 10 weight % or lower.
 10. Thenon-aqueous liquid electrolyte as defined in claim 8, wherein in saidnon-aqueous liquid electrolyte, the concentration of said carbonatehaving at least either an unsaturated bond or a halogen atom is 0.01weight % or higher, and 70 weight % or lower.
 11. The non-aqueous liquidelectrolyte as defined in claim 8, wherein said carbonate having anunsaturated bond or a halogen atom is one or more carbonate compoundsselected from the group consisting of vinylene carbonate, vinylethylenecarbonate, fluoroethylene carbonate, difluoroethylene carbonate andderivatives of these carbonate compounds.
 12. The non-aqueous liquidelectrolyte as defined in claim 8, further comprising ethylene carbonateand/or propylene carbonate.
 13. The non-aqueous liquid electrolyte asdefined in claim 8, further comprising at least one additional carbonateselected from the group consisting of dimethyl carbonate, ethylmethylcarbonate, diethyl carbonate, methyl-n-propyl carbonate, ethyl-n-propylcarbonate and di-n-propyl carbonate.
 14. A non-aqueous liquidelectrolyte secondary battery comprising an anode electrode and acathode electrode, capable of intercalating and deintercalating lithiumions, and a non-aqueous liquid electrolyte, the anode electrodecontaining an anode electrode active material having at least one kindof atom selected from the group consisting of Si atom, Sn atom and Pbatom, wherein said non-aqueous liquid electrolyte is the non-aqueousliquid electrolyte defined in claim
 8. 15. The non-aqueous liquidelectrolyte as defined in claim 1, wherein said compound represented byformula (III-1) is a compound represented by formula (III-2)

wherein in formula (III-2), X¹ and X² represent, independently of eachother, an element other than hydrogen, Z represents an arbitrary elementor group, m and n represent, independently of each other, an integergreater than or equal to 1, and when m is 2 or greater, each of Z may bethe same or different from each other.
 16. The non-aqueous liquidelectrolyte as defined in claim 8, wherein said compound represented byformula (III-1) is a compound represented by formula (III-2)

wherein in formula (III-2), X¹ and X² represent, independently of eachother, an element other than hydrogen, Z represents an arbitrary elementor group, m and n represent, independently of each other, an integergreater than or equal to 1, and when m is 2 or greater, each of Z may bethe same or different from each other.